==========================================================================
=                                                                        =
=       This files conatins a history of the HDF4.* releases.            =
=                                                                        =
=       To find information about a particular release search            =
=       for %%%4.#r# string, for example 4.1r2.                          =
=       List of all releases is on the top of the file.                  =
=                                                                        =
=       Documents in this file refer to several *.txt files that were    =
=       originally stored in the release_notes directory of the HDF4     =
=       source tree. Those file are now combined into one misc_docs.txt  =
=       file in the same directory.                                      =
=                                                                        =
==========================================================================    

List of the HDF4 releases

4.2r4          January   2009
4.2r3          January   2008
4.2r2          October   2007
4.2r1          February  2005
4.2r0          December  2003
4.2r0-Beta     September 2003
4.1r5          November  2001
4.1r4          October   2000
4.1r3          May       1999
4.1r2          March     1998 
4.1r1          February  1997
4.1b1          December  1996 
4.0r2          July      1996 
4.0r1          February  1996
4.0b2          November  1995
4.0b1          July      1995 
4.0.alpha      November  1994


==========================================================================    
 
%%%4.2r4%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


                          HDF 4.2 Release 4  
                          =================
                          January 25, 2009

INTRODUCTION

This document describes the differences between HDF 4.2r3 and HDF 4.2r4
It is written for people who are familiar with previous releases of HDF 
and wish to migrate to HDF 4.2r4

The HDF 4.2r4 documentation can be found on the The HDF Group's FTP server:

     ftp://ftp.hdfgroup.org/HDF/Documentation/

First-time HDF users are encouraged to read the HDF FAQ, which can be
reached from the HDF product home page:
  
     http://hdfgroup.org/products/hdf4/

If you have any questions or comments, please see the HDF Support page:

     http://hdfgroup.org/services/support.html

CONTENTS

- New features and changes
  -- Configuration
  -- Library
  -- Utilities
- Support for new platforms and compilers
- Bugs fixed since HDF4.2r3
  -- Utilities
  -- Library
  -- Configuration
- Documentation
- Platforms tested
- Known problems


New features and changes
========================
    Configuration
    ============= 
        - Automake 1.10.1 used to generate Makefile.in files, and 
          Autoconf 2.61 used to generate configure script. MAM - 2008/10/09
        - Libtool support (2.2.6a) has been added, and HDF4 shared C 
          libraries can now be built. To build, use the --enable-shared 
          configuration flag. This needs to be used in conjunction with 
          the --disable-fortran flag, as Fortran shared libraries are not 
          supported. Shared libraries are disabled by default. 
          MAM - 2008/10/09
        - Added SZIP information to end of configure summary, which indicates
          whether SZIP is present and, if SZIP is present, whether the SZIP
          encoder is present.  MAM - 2008/10/06

    Library
    ========= 
        - Added new API SDgetdatasize to retrieve the compressed and original
          sizes of an SDS' data.  Its limitation is listed in the "Known 
          problems" section at the end of this document.
          intn SDgetdatasize(int32 sdsid, int32* comp_size, int32* orig_size)
                sdsid     - IN: dataset ID
                comp_size - OUT: size of compressed data
                orig_size - OUT: size of original data 
          BMR - 2008/10/15

        - The following Fortran APIs were added in this release:
                sfgetname
                sfgetnamelen
                sfgmaxopenf
                sfgnumopenf
                sfrmaxopenf
                sfidtype
                sfgnvars_byname
                sfn2indices
          Please see HDF Reference Manual for functions description.
          Note: These APIs are not available on Windows.

    Utilities
    ========= 
        - hrepack output now includes dataset compression ratios.
          PVN - 2008/10/30
        - hdp now displays various parameters of Gzip, Szip, and Skipping
          Huffman compressions when a dataset is compressed. (Bugzilla 1202)
          BMR - 2008/10/03


Support for new platforms and compilers
=======================================
        Linux 2.6.27 x86_64 Fedora 10 with GNU C and gfortran
                            Ubuntu 8.10 with GNU C and gfortran
                            OpenSuse 11.1 with GNU C and gfortran

        Mac Intel with GNU C, gfortran, g95 and Intel 10.1 32-bit 
        C and Fortran compilers

          Note: Only the 32-bit version of the Intel compiler is supported. 

          One has to run configuration scripts, which can be found under 
          the bin directories in the Intel compiler installation directory 
          tree (e.g., /opt/intel/cc/10.1.006/bin/iccvars.csh and 
          /opt/intel/fc/10.1.006/bin/ifortvars.csh), to enable the
          32-bit version of the compiler before configuring and building HDF4.

          Known problems: 
          Due to a known bug in the Intel 10.1 icc compiler, one has to use
          -no-multibyte-chars flag with icc. O0 flag with ifort is required
          to build Fortran APIs and tests. This restriction is probably due
          to very old Fortran code and will be lifted for future releases.  
        

Bugs fixed since HDF4.2r3
=========================
    Utilities
    ========= 
        - hrepack previously failed to preserve unlimited dataset dimensions; 
          they are now preserved.  PVN - 2008/11/19

    Library
    ========= 
        - SDreaddata now checks for out-of-range values in the parameter 
          'stride' and fails when invalid values are given (Bugzilla 150.)  
          This bug was actually fixed right before the HDF4.2r2 release.  
          BMR - 2008/07/14
        - Reading a record variable using nc API fills the buffer with fill
          values up to the maximum number of records of all unlimited
          dimension variables in the file, as in netCDF.  It used to fail
          before (Bugzilla 1378.) - BMR 2009/01/21
        - When the file name is too long, some SD APIs caused a segmentation 
          fault (Bugzilla 1331.)  This problem is now fixed. - BMR 2009/01/23

    Configuration
    ============= 
        - hdiff_array.c now gets linked against libm.a library. 

Documentation
==============
The updated HDF Reference Manual is now available in HTML format.

Platforms tested
================

HDF 4.2 Release 4 has been tested on the following platforms:

    FreeBSD 6.3-STABLE i386       gcc 3.4.6 [FreeBSD] 20060305
    (duty)                        g++ 3.4.6 [FreeBSD] 20060305
                                  f77 (gcc) 3.4.6
                                  gcc 4.2.5 20080702
                                  g++ 4.2.5 20080702
                                  gfortran 4.2.5 20080702

    FreeBSD 6.3-STABLE amd64      gcc 3.4.6 [FreeBSD] 20060305
    (liberty)                     g++ 3.4.6 [FreeBSD] 20060305
                                  f77 (gcc) 3.4.6
                                  gcc 4.2.5 20080702
                                  g++ 4.2.5 20080702
                                  gfortran 4.2.5 20080702

    IRIX64 6.5                    MIPSpro cc 7.4.4m
    (ucar mop1 64 & n32)          F90 MIPSpro 7.4.4m


    Linux 2.6.18-92.1.22.el5xen   gcc (GCC) 4.1.2 20071124
         #1 SMP i686 i686 i386    gG95 (GCC 4.0.3 (g95 0.92!) July 1 2008)
    (jam)                         g77 (GCC) 3.4.6 20060404
                                  PGI C, Fortran, C++ 7.2-5 32-bit
                                  Intel(R) C Compiler for 32-bit
                                      applications, Version 10.1.018
                                  Intel(R) Fortran Compiler for 32-bit
                                      applications, Version 10.1.018

    Linux 2.6.9-42.0.10.ELsmp #1  gcc (GCC) 3.4.6
         SMP i686 i386            g++ (GCC) 3.4.6
    (kagiso)                      G95 (GCC 4.0.3 (g95 0.92!) April 18 2007)

    Linux 2.6.16.46-0.12-debug #1 Intel(R) C Compiler Version 10.0.025
        SMP ia64 GNU/Linux        Intel(R) Fortran Itanium(R) Version 10.0.025
    (ucar hir1)

    Linux 2.6.16.46-0.14-smp #1   gcc (GCC) 4.1.2 20070115 (SUSE Linux)
        SMP x86_64 GNU/Linux      G95 (GCC 4.0.3 (g95 0.92!) July 1 2008)
    (smirom)                      Intel(R) C Compiler for Intel(R) EM64T Ver.
10.1.013
                                  Intel(R) Fortran Intel(R) EM64T Ver.
10.1.013
                                  PGI C, Fortran Version 7.2-1
                                         for 64-bit target on x86-64

    Linux 2.6.16.54-0.2.5 #1      Intel(R) C Compiler Version 10.1.017
        Altix SMP ia64            Intel(R) Fortran Itanium(R) Version 10.1.017
    (cobalt)                      SGI MPI 1.16

    SunOS 5.10 32- and 64-bit     Sun WorkShop 6 update 2 C 5.8
                                  Patch 121015-06
    (linew)                       Sun WorkShop 6 update 2 Fortran 95 8.2
                                  Patch 121019-09

    Xeon Linux 2.6.18-92.1.10.el5_lustre.1.6.6smp-perfctr
         #2 SMP x86_64            Intel(R) C Compiler Version 10.0.026
    (abe)                         Intel(R) Fortran Compiler Version 10.0.026

    IA-64 Linux 2.4.21.SuSE_292.til1
        ia64
    (NCSA tg-login)               Intel(R) C Compiler Version 8.1.037
                                  Intel(R) Fortran Compiler Version 8.1.033


    Windows XP                    Visual Studio 6.0
                                  Visual Studio .NET (with Intel Fortran 9.1)
                                  Visual Studio 2005 (with Intel Fortran 9.1/10.1)
                                  Visual Studio 2008 (with Intel Fortran 10.1)
                                  cygwin (gcc 3.4.4 and g95 0.90!)

    Windows XP(64 bit)            Visual Studio 2005 (with Intel Fortran 9.1/10.1)
                                  Visual Studio 2008 (with Intel Fortran 10.1)
                                  
    Windows Vista                 Visual Studio 2008 (with Intel Fortran 10.1)
                                  cygwin (gcc 3.4.4 and g95 0.90!)
                                  
    Windows Vista(64 bit)         Visual Studio 2008 (with Intel Fortran 10.1)
                                  
    MAC OS X Intel                Darwin 9.4.0
                                  i686-apple-darwin8-gcc-4.0.1 (GCC) 4.0.1
                                  G95 (GCC 4.0.3 (g95 0.91!) Apr 24 2008)
                                  gfortran GNU Fortran (GCC) 4.3.0 20070810
                                  Intel 10.1 32-bit version

    Linux 2.6.27.9-159.fc10.x86_64 #1 SMP 
        x86_64 GNU/Linux          gcc (GCC) 4.3.2
     (Fedora 10)                  gfortran GNU Fortran (GCC) 4.3.2 20081105 
                                                       (Red Hat 4.3.2-7)
    Linux 2.6.27-9-generic #1 SMP 
        x86_64 GNU/Linux          gcc (GCC) 4.3.2
     (Ubuntu 8.10)                gfortran GNU Fortran (GCC) 4.3.2 
                                                       
    Linux 2.6.27.7-9-default #1 SMP 
        x86_64 GNU/Linux          gcc (GCC) 4.3.2
     (OpenSuse 11.1)              gfortran GNU Fortran (GCC) 4.3.2 


Known problems
==============

o  Existing data written by an HDF4 Library prior to HDF 4.2r2:
   When a one-dimensional SDS and a dimension scale were created with
   the same name, subsequent accesses to the dimension scale or to the
   SDS might corrupt the data.

   HDF4 Library Releases 4.2r2 and later do not allow this conflict to
   occur.  On the other hand, recent libraries are also unable to detect
   such conflicts that already exist in a file.  It is therefore STRONGLY
   recommended to check for such name duplication before working with data 
   created with a pre-4.2r2 library. 

   The functions SDgetnumvars_byname and SDnametoindices are provided
   to help detect such name conflicts and select the correct object to
   access, respectively; see the HDF Reference Manual entries for 
   further details.

o  This release does not support VMS systems.

o  N-Bit compression is not supported with Fortran APIs.

o  Using both fill-value and compression on SD datasets does not work.

o  When using PGI compilers, make sure that the JPEG library is also compiled 
   with a PGI C compiler; linking with a JPEG library built with gcc causes 
   JPEG library tests to fail.  To bypass the problem:

       x Set LIBS flag to $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a
         where $PGI_JPEG_INSTALL_DIR points to the installation directory
         for the PGI-compiled JPEG library:

         setenv LIBS $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a

       x Use the --with-jpeg=$PGI_JPEG_INSTALL_DIR configure flag to 
         configure with the PGI-compiled JPEG library:

         ./configure --with-jpeg=$PGI_JPEG_INSTALL_DIR --with-zlib....

o  In order for the new API SDgetdatasize to get the correct compressed size
   of the data, the dataset needs to be closed (SDendaccess) or read
   (SDreaddata), after being written and before SDgetdatasize is called.

o  On a fedora x86_64 GNU/Linux machine with gfortran 4.3.2, the flag
   -fno-range-check needs to be used to work around old code.
   
o  On Windows with Visual Studio .NET 2003, a minor bug in the hdfnctest test
    causes it to fail.  The failure is non-critical, and so the test has been
    disabled by default for all Windows compilers.
   
==========================================================================    
 
%%%4.2r3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


                          HDF 4.2 Release 3
                          =================
                          January 28, 2008

INTRODUCTION

This document describes the differences between HDF 4.2r2 and HDF 4.2r3.  
It is written for people who are familiar with previous releases of HDF 
and wish to migrate to HDF 4.2r3.

The HDF 4.2r3 documentation can be found on the THG ftp server:

     ftp://ftp.hdfgroup.org/HDF/Documentation/

First-time HDF users are encouraged to read the HDF FAQ, which can be
reached from the HDF product home page:
  
     http://hdfgroup.org/products/hdf4/

If you have any questions or comments, please see the HDF Support page:

     http://hdfgroup.org/services/support.html

CONTENTS

- New features and changes
  -- Configuration
  -- Library
  -- Utilities
- Support for new platforms and compilers
- Bugs fixed since HDF4.2r2
  -- Utilities
  -- Library
  -- Configuration
- Documentation
- Platforms tested
- Known problems


New features and changes
========================
    Configuration
    ============= 
    None 

    Library
    ========= 

	- Modified the HDF4 mfhdf library and configure to work in the 
	  absence of the NetCDF-3 header files when the HDF4 library 
	  is configured with the --disable-netcdf flag. This feature is 
	  required when building the ESDIS Toolkit in the presence of the
	  NetCDF-3 library. In this case, the HDF4 file netcdf.h is used 
	  to build the HDF4 libraries and is installed under the name 
	  "hdf4_netcdf.h" to avoid a name clash with the NetCDF-3 file 
	  netcdf.h.
							EIP 2007-10-30

	- Note that the previous change to SDnametoindex was backed out.  It 
	  only returns the first variable of the requested name, as did the 
	  original version of this function.  The variable can be an SDS or 
	  a coordinate variable.  With this behavior, if there is more than
	  one variable with the same name in the file, care must be taken to
	  retrieve the desired variable.  Please see new APIs in the next 
	  item for a way to handle non-uniquely named variables.  The behavior 
	  of SDnametoindex will be documented in FAQs, documentation, and the
	  newsletter.
							BMR 2008-01-17

	- Added new APIs to SD interface:
	  + SDgetnumvars_byname: Given a name, returns the number of 
	    variables in a file with that same name.
	  + SDnametoindices: Given a name, returns a list of indices of 
	    all the variables in a file with that same name.
	  With these new APIs, users can determine when an SDS name or 
	  a coordinate variable's name is not unique, retrieve the named 
	  variables, and examine them.
							BMR 2008-01-17

    Utilities
    ========= 
        None 


Support for new platforms and compilers
=======================================
        
    Support for Windows XP 64-bit with Visual Studio 2005 and 
    Intel Fortran compiler was added. 

Bugs fixed since HDF4.2r2
=========================
    Utilities
    ========= 
        None

    Library
    ========= 
        None

    Configuration
    ============= 
       - libhdf4.settings file was not installed by make install command;
         fixed
                                                         EIP, 2007-10-09


Documentation
==============
     Descriptions of the new functions SDgetnumvars_byname and SDnametoindices
     have been added to the documentation. 


Platforms tested
================

HDF 4.2 Release 3 has been tested on the following platforms:

                                  
    AIX 5.2 (32/64 bit)           xlc 8.0.0.11
    (datstar)                     xlf 10.01.0000.0002

    FreeBSD 6.2 (32- and 64-bit)  gcc  and f77 GNU 3.4.6
    (duty and liberty)            GNU Fortran (GCC) 4.2.3 20080123 

    IRIX64 6.5                    MIPSpro cc 7.4.4m
    (ucar mop1 64 & n32)          F90 MIPSpro 7.4.4m 

    Linux 2.4.21-47.ELsmp #1 SMP  gcc and g77 3.2.3
        i686 i386 GNU/Linux
    (osage)

    Linux 2.6.9-42.0.10.ELsmp #1  gcc (GCC) 3.4.6
        SMP i686 i386             G95 (GCC 4.0.3 (g95 0.91!) April 18 2007)
    (kagiso)                      PGI C, Fortran 7.0-7 32-bit 
                                  icc (ICC) 9.1 
                                  Intel(R) Fortran Compiler for 32-bit 
                                      applications, Version 9.1 

    Linux 2.6.16.46-0.12-debug #1 Intel(R) C++ Version 10.0.025
        SMP ia64 GNU/Linux        Intel(R) Fortran Itanium(R) Version 10.0.025
    (ucar hir1)                   

    Linux 2.6.16.46-0.14-smp #1   Intel(R) C for Intel(R) EM64T Ver. 9.1.037
        SMP x86_64 GNU/Linux      Intel(R) Fortran Intel(R) EM64T Ver. 9.1.031
    (smirom)                      gcc (GCC) 4.1.2 20070115 (SUSE Linux)
                                  G95 (GCC 4.0.3 (g95 0.91!) Apr 19 2007)

    Linux 2.6.5-7.283-rtgfx Altix Intel(R) C++ Version 9.0.032
        SMP ia64                  Intel(R) Fortran Itanium(R) Version 9.0.033
    (cobalt)                      

    SunOS 5.8 32- and 64-bit      Sun WorkShop 6 update 2 C 5.3
    (sol)                         Sun WorkShop 6 update 2 Fortran 77 5.3

    SunOS 5.10 32- and 64-bit     Sun WorkShop 6 update 2 C 5.8 
                                  Patch 121015-06
    (linew)                       Sun WorkShop 6 update 2 Fortran 95 8.2
                                  Patch 121019-09 

    IA-64 Linux 2.4.21.SuSE_292.til1
        ia64                      
    (NCSA tg-login)               Intel(R) C++ Version 8.1.037
                                  Intel(R) Fortran Compiler Version 8.1.033

    Windows XP                    Visual Studio 6.0
                                  Visual Studio .NET (with Intel Fortran 9.1)
                                  Visual Studio 2005 (with Intel Fortran 9.1)
                                  cygwin (gcc 3.4.4)

    Windows XP(64 bit)            Visual Studio 2005(with Intel Fortran 9.1)
                                  
    Windows Vista                 Visual Studio 2005 (no fortran)
                                  
    MAC OS X Intel                Darwin 8.10.1
                                  i686-apple-darwin8-gcc-4.0.1 (GCC) 4.0.1
                                  g95 0.91
                                  gfortran GNU Fortran (GCC) 4.3.0 20070518


Known problems
==============

o  hdfcomp fails on HPUX 11.23 for the 64-bit version of the library.

o  This release does not support VMS systems.

o  N-Bit compression is not supported with Fortran APIs.

o  Using both fill-value and compression on SD datasets does not work.

o  For existing data prior to HDF 4.2r2, when a one-dimensional SDS has the 
   same name as the dimension scale, subsequent accesses to the dimension scale
   or the SDS might produce undesired results.  It is recommended to check
   for name duplication first.  See "New features and changes" section for 
   details.

o  When using PGI compilers, make sure that the JPEG library is also compiled 
   with a PGI C compiler; linking with a JPEG library built with gcc causes 
   JPEG library tests to fail.  To bypass the problem:

       x Set LIBS flag to $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a
         where $PGI_JPEG_INSTALL_DIR points to the installation directory
         for the PGI-compiled JPEG library:

         setenv LIBS $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a

       x Use the --with-jpeg=$PGI_JPEG_INSTALL_DIR configure flag to 
         configure with the PGI-compiled JPEG library:

         ./configure --with-jpeg=$PGI_JPEG_INSTALL_DIR --with-zlib....

%%%4.2r2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%




                          HDF 4.2 Release 2
                          October 4, 2007

INTRODUCTION

This document describes the differences between HDF 4.2r1 and
HDF 4.2r2.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.2r2.

The HDF 4.2r2 documentation can be found on the THG ftp server 
(ftp.hdfgroup.org) in the directory:

     ftp://ftp.hdfgroup.org/HDF/Documentation/

First-time HDF users are encouraged to read the FAQ for this
release for more information about HDF.  Also see the home page 
for HDF at:

     http://hdfgroup.org/

If you have any questions or comments, please send them to:

     help@hdfgroup.org

CONTENTS

- New features and changes
  -- Configuration
  -- Library
  -- Utilities
- Support for new platforms and compilers
- Bugs fixed since HDF4.2r1
  -- Utilities
  -- Library
- Documentation
- Platforms tested
- Known problems

New features and changes
========================
    Configuration
    ============= 
        - The default installation directory name was changed from "NewHDF" 
          to "hdf4".                            EIP - 2007/08/06
        - Introduced --enable-netcdf configure flag to provide an option to
          enable/disable "HDF4-NetCDF"-like interfaces. By default, the 
          HDF4 netcdf feature is enabled.  Use the --disable-netcdf 
          configuration flag to build HDF4 C and Fortran libraries that can 
          be used by NetCDF-3 applications. There is no longer a need to 
          specify the -DHAVE_NETCDF compilation flag.  This feature is not 
          yet supported on Windows.             EIP - 2007/09/05
        - Updated versions of autotools. HDF4 now uses automake 1.10.0,
          autoconf 2.61, and libtool 1.5.22.    MAM - 2007/7/25.
        - The Fortran part of the HDF4 library uses the F77_FUNC macro to 
          mangle names of C functions called from Fortran APIs. This should 
          help with HDF4 code portability to different Fortran compilers.
                                                EIP - 2006/12/19
     
    Library
    ========= 
        - SZIP compression is supported now for GR C interfaces
                                                EIP - 2007/09/15
        - Added new Fortran function hconfinf that determines whether the 
          SZIP compression method is present and whether encoding is available.
        - Added support for SZIP compression in Fortran.
                                                EIP - 2007/09/01
        - The following APIs were added; see "Bugs fixed" section for details.
          SDreset_maxopenfiles -- Resets the maximum number of files that can 
                  be open at a time.
          SDget_maxopenfiles -- Retrieves the current number of open files
                  allowed in HDF and the maximum number of open files allowed 
                  on a system.
          SDget_numopenfiles -- Returns the number of files currently open.
          SDgetcompinfo -- Replaces SDgetcompress.
          GRgetcompinfo -- Replaces GRgetcompress.
          SDgetfilename -- Retrieves the name of the file, given its ID.
          SDgetnamelen -- Retrieves the name length of the object, given its ID.
          Note: Fortran wrappers for these new APIs are not available in this 
          release.  BMR - 2007/09/23
        - SDS and vgroup names are no longer limited to 64 characters
          (Bugzilla #516).  Note that when an older version of the library 
          reads a new name that is longer than 64 characters, the name will
          contain some garbage after 64 characters.  BMR - 2006/10/12
        - User reported that SDreaddata went into an infinite loop when 
          reading some corrupted compressed data.  This problem is fixed.
          Two new error codes were added, consequently:
                DFE_READCOMP  - when the zlib function returns
                        Z_ERRNO        (-1) or
                        Z_STREAM_ERROR (-2) or
                        Z_DATA_ERROR   (-3) or
                        Z_MEM_ERROR    (-4) or
                        Z_BUF_ERROR    (-5)

                DFE_COMPVERSION - when the zlib function returns
                        Z_VERSION_ERROR (-6)


    Utilities
    ========= 
        - hrepack repacks by hyperslabs for large (non-compressed) datasets.
                                                         PVN - 2007/7/10
        - hdiff enables reading by hyperslabs. This feature was added to 
          handle very large datasets, where available memory is a isssue. 
                                                         PVN - 2007/6/13
        - hdiff now shows indices in multidimensional array notation. 
                                                         PVN - 2007/4/5
        - hdiff now shows the name of the array when printing differences. 
                                                         PVN - 2007/4/5
        - hdiff now shows a list of all objects in verbose mode. 
                                                         PVN - 2007/4/5
        - hdiff return code is now 1 if differences are found, 0 if no
          differences are found, and -1 for an error.    PVN - 2007/4/5
        - hdiff has a new option, -p, for relative error. See usage. 
                                                         PVN - 2007/4/5
        - hrepack now prints chunk information along with the compression 
          type in verbose mode.                          PVN - 2007/4/5
         

Support for new platforms and compilers
=======================================
        - Added support for gfortran and g95 on Mac Intel.
                                       EIP 2007/09/14
        - Added support for gfortran on FreeBSD for both 32- and 64-bit. 
        - Added support for FreeBSD on AMD64 with gcc compilers.
                                       EIP 2007/05/24
        - Added support for MAC OS X Intel with gcc and g95 compilers.
        - Added support for SUNOS 5.10 on Intel with SUN compilers (32- and
          64-bit modes).               EIP 2006/12/14
        - Added support for HPUX 11.23 (32- and 64-bit modes).
                                        EIP 2006/12/19

Bugs fixed since HDF4.2r1
=========================
     Utilities
    ========= 
        - hrepack: Repeated vgroup insertions (duplicated links) were not being 
          replicated.  PVN - 2007/9/10
        - hrepack: Improved performance for large number of SDSs, through the 
          elimination of redundant file open calls.  PVN - 2007/4/5
        - hrepack: Fixed a bug in the -t option so that it now accepts multiple
          comma-separated names.  PVN - 2007/4/5
        - hrepack: Now duplicates dimension SDSs that are not accessed from any 
          other SDSs.  PVN - 2007/4/5
        - hrepack: Fixed a bug that caused the unchunking of a dataset when
          uncompressing was requested.  PVN - 2007/4/5

    Library
    ========= 
        - Added display of the compression method to hdp dumpsds and dumpgr
          (Bugzilla #130).  BMR - 2005/4/4
        - The current SDgetcompress and GRgetcompress APIs have severe flaws.
          Two new APIs, SDgetcompinfo and GRgetcompinfo, were added to 
          provide better functionality and will eventually replace 
          SDgetcompress and GRgetcompress.  BMR - 2005/4/4
        - Applied user's patch to fix bug #602.  BMR - 2005/4/23
        - Added a switch ('u') to ncdump to replace nonalpha-numeric characters
          with underscores.  Thus, the SDS names won't be changed automatically 
          unless the user so requests (Access bug #934/Bugzilla #381).
          BMR - 2005/7/17
        - In HDF4.2r0, SDwritedata failed when the SDS had rank=0 (bug #1045).
          This change was retracted; writing to an SDS with rank=0 is allowed 
          again.  BMR - 2005/8/23
        - When a dimension has the same name as an SDS, depending on the
          order in which they were created, either the SDS or the dimension
          will be corrupted if certain operations occur, such as a SDsetdimscale
          or SDsetattr call to the dimension.  With this bugfix, the current 
          situation can be summarized as below:
              + Data that has already been corrupted cannot be recovered.
              + For existing data that has not yet been corrupted, the problem 
                has been fixed for multi-dimensional SDSs only.  If the SDS had
                only one dimension, the results of subsequent accesses to the 
                dimension would still be unpredictable (Bugzilla #328).  
                BMR - 2005/8/23
              + For future data, the problem has been fixed (Bugzilla #624).
                BMR - 2007/6/24
        - Allowing the maximum number of open files to be increased revealed
          a problem: having more than 255 files open will cause file
          corruption (Bugzilla #440).  Specifically, file number (255*m)+n 
          will overwrite file number n, where n is [0..255] and m is [1..p], 
          where (255*p) <= maximum system allowed.  This problem is fixed.
          In addition, a new API is added for convenience:
                SDgetfilename -- retrieves the name of the file given its ID.
          BMR - 2005/10/05
        - Prior to this release, the maximum number of files that can be open
          at the same time was only 32. This limit was implemented as a 
          defined constant in the library, which users could not change without 
          recompiling the library. In this release, if this limit is reached, 
          the library will increase it to the system limit, minus 3 to account 
          for stdin, stdout, and stderr.  In addition, three APIs are added 
          for more flexibility (Bugzilla #396/Access bug #935):  
                SDreset_maxopenfiles -- Resets the maximum number of files 
                        that can be open at a time.
                SDget_maxopenfiles -- Retrieves the current number of open 
                        files allowed in HDF and the maximum number of open 
                        files allowed on a system.
                SDget_numopenfiles -- Returns the number of files currently 
                        open.
          Note:
            (1) Because there are also stdin, stdout, and stderr, the maximum
                limit that can be set must only be (system limit) - 3.
            (2) If the system maximum limit is reached, the library will 
                push the error code DFE_TOOMANY onto the error stack.
                The user application can detect this after an SDstart fails.
          BMR - 2005/10/21
        - The problem where ncgen failed with "too many attributes" on 
          some user files is fixed (Bugzilla #373).  BMR - 2005/10/28
        - The problem where SDcheckempty returns "not empty" for empty 
          chunked and compressed datasets is fixed (Bugzilla #218).
          BMR - 2005/10/31
        - If a VSgetattr was called twice for an attribute, the second call 
          would fail (Bugzilla #486).  This problem is fixed.  BMR - 2005/12/30
        - A bug with reading metadata in hdfimport is fixed (Bugzilla #558).
          BMR - 2006/9/23
        - The problem of writing to two unlimited 1-D arrays is fixed
          (Access bug #525).  BMR - 2006/11/11

Documentation
==============
    Documentation contains multiple bug fixes and improvements. 

Platforms tested
================

HDF 4.2 Release 2 has been tested on the following platforms:

                                  
    AIX 5.3 (32/64 bit)           xlc 7.0.0.0
    (copper)                      xlf 9.1.0.3

    FreeBSD 6.2 (32- and 64-bit)  gcc  and f77 GNU 3.4.6
    (duty and liberty)            GNU Fortran (GCC) 4.2.2 20070905 

    HP-UX B.11.23 (32- and 64-bit)HP aC++/ANSI C B3910B A.06.02
    (sirius)                      HP F90 v3.1 

    IRIX64 6.5                    MIPSpro cc 7.4.4m
    (ucar mop1 64 & n32)          F90 MIPSpro 7.4.4m 

    Linux 2.4.21-47.ELsmp #1 SMP  gcc and f77 3.2.3
        i686 i386 GNU/Linux
    (osage)

    Linux 2.6.9-42.0.10.ELsmp #1  gcc (GCC) 3.4.6
        SMP i686 i386             G95 (GCC 4.0.3 (g95 0.91!) Nov 21 2006)
    (kagiso)                      PGI C, Fortran, C++ 6.2-5 32-bit 
                                  icc (ICC) 9.1 
                                  Intel(R) Fortran Compiler for 32-bit 
                                      applications, Version 9.1 

    Linux 2.6.16.46-0.12-debug #1 
        SMP ia64 GNU/Linux        Intel(R) C++ Version 10.0.025
    (ucar hir1)                   Intel(R) Fortran Itanium(R) Version 10.0.025

    Linux 2.6.16.46-0.14-smp #1   Intel(R) C++ for Intel(R) EM64T Ver. 9.1.037
        SMP x86_64 GNU/Linux      Intel(R) Fortran Intel(R) EM64T Ver. 9.1.031
    (smirom)                      gcc (GCC) 4.1.2 20070115 (SUSE Linux)
                                  G95 (GCC 4.0.3 (g95 0.91!) Apr 19 2007)

    Linux 2.6.5-7.283-rtgfx Altix 
        SMP ia64                  Intel(R) C++ Version 9.0
    (cobalt)                      Intel(R) Fortran Itanium(R) Version 9.0


    SunOS 5.8 32- and 64-bit      Sun WorkShop 6 update 2 C 5.3
    (sol)                         Sun WorkShop 6 update 2 Fortran 95 6.2

    SunOS 5.10 32- and 64-bit     Sun WorkShop 6 update 2 C 5.8
    (linew)                       Sun WorkShop 6 update 2 Fortran 95 8.2
                                  Patch 121019-06 


    IA-64 Linux 2.4.21.SuSE_292.til1
        ia64                      gcc (GCC) 3.2.2
    (NCSA tg-login)               Intel(R) C++ Version 8.0
                                  Intel(R) Fortran Compiler Version 8.0

    Windows XP                    Visual Studio 6.0
                                  Visual Studio .NET (with Intel Fortran 9.1)
                                  Visual Studio 2005 (with Intel Fortran 9.1)
                                  cygwin (gcc 3.4.4)
                                  
    Windows Vista                 Visual Studio 2005 (no fortran)
                                  
    MAC OS X Intel                Darwin 8.10.1
                                  i686-apple-darwin8-gcc-4.0.1 (GCC) 4.0.1
                                  g95 0.91
                                  gfortran GNU Fortran (GCC) 4.3.0 20070518

                                  

Known problems
==============

o  hdfcomp fails on HPUX 11.23 for the 64-bit version of the library

o  This release does not support VMS systems.

o  N-Bit compression is not supported with Fortran APIs.

o  Using both fill-value and compression on SD datasets does not work.

o  When a one-dimensional SDS has the same name as the dimension, subsequent
   accesses to the dimension produce unpredictable results.

o  When using PGI compilers, make sure that the JPEG library is also compiled 
   with a PGI C compiler; linking with JPEG built with gcc causes JPEG library 
   tests to fail.  To bypass the problem:

       x Set LIBS flag to $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a
         where $PGI_JPEG_INSTALL_DIR points to the installation directory
         for the PGI-compiled JPEG library:

         setenv LIBS $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a

       x Use the --with-jpeg=$PGI_JPEG_INSTALL_DIR configure flag to 
         configure with the PGI-compiled JPEG library:

         ./configure --with-jpeg=$PGI_JPEG_INSTALL_DIR --with-zlib....

%%%4.2r1%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



                          HDF 4.2 Release 1
                            February, 2005

INTRODUCTION

This document describes the differences between HDF 4.2r0 and
HDF 4.2r1.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.2r1

The HDF 4.2r1 documentation can be found on the NCSA ftp server 
(ftp.ncsa.uiuc.edu) in the directory:

     ftp://hdf.ncsa.uiuc.edu/HDF/Documentation/

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
  -- Configuration
  -- Library
  -- Utilities
- Support for new platforms and compilers
- Bugs fixed since HDF4.2r1
- Documentation
- Platforms Tested
- Known problems

New Features and Changes:
========================
    Configuration
    ============= 
     
     * By default HDF4 libraies and utilities are installed under 
       <source_dir>/NewHDF
                                               12/01/2004 EIP
     * Windows configuration, build and testing procedures have been changed. 
       Please see INSTALL_WINDOWS.txt file for more information
                                               02/12/2005 EIP 
    Library
    ========= 
    * New API SDidtype was added to the library (bug #766)
                                               01/23/2005 EIP for BMR
    * HCgetcompress renamed to HCPgetcompress
    * New API HCget_config_info added
    * The default chunk cache size was changed for 2D and higher
      chunks
    * Pablo instumentation was removed
   
    Utilities
    ========= 
     * hdiff and hrepack are supported on Windows.
     * Substantial performance improvements in hdiff and hrepack

Support for new platforms and compilers
=======================================
     * Fortran IBM xlf v 8.1 and Absoft f95 version 8.2 compilers 
       are supported on Mac OSX.
                                                          12/07/2004 EIP
     * Absoft Fortran compiler f95 version 9.0 is supported on Linux 2.4 
                                                          12/07/2004 EIP
     * PGI C and Fortran compilers are supported on Linux 2.4 
     * Intel C and Fortran compilers are supported on Linux 2.4
     * AMD Opteron is supported


Bugs fixed since HDF4.2r0
=========================
 * VERY IMPORTANT:
   Data compressed with SZIP may be corrupted; fixed. For more
   information see "HDF4.2r1 SZIP Release Notes" available at
   http://hdf.ncsa.uiuc.edu/doc_resource/SZIP/SZIP_HDF4_2r1.pdf
                                            02/12/2005 EIP 
 * Fortran couldn't read names with spaces when NetCDF interfaces
   were used; fixed
                                            02/12/2005 EIP
 * Library failed to compile in presence of the NetCDF library; fixed
                                            11/22/2004 EIP
 * h4fc couldn't create object files; fixed 

                                            01/23/2005 EIP
 * When rank of SDS is 0, some SD APIs give segmentation fault (bug 1045);
   fixed
                                            01/23/2005 EIP for BMR
 * Some GR images with special elements are read in as duplicate
   (bug 814); fixed
                                            02/14/2005 BMR

 * Many bugs fixed in hdiff and hrepack utilities

Documentation
==============
   Documentation contains multiple bug fixes and improvements. 

Platforms Tested
================

HDF 4.2 Release 1 has been tested on the following platforms:

    AIX 5.1  (32 and 64-bit)      xlc 6.0.0.6
                                  xlf 8.1.1.6
    AIX 5.2  (32 and 64-bit)      xlc 6.0.0.8
                                  xlf 8.1.1.7
    Cray SV1 10.0.1.2             Cray Standard C Version 6.6.0.3.6
                                  Cray Fortran: Version 3.6.0.3.1
    Cray TS IEEE                  Cray Standard C Version 6.4.0.3
                                  Cray Fortran: Version 3.4.0.0

    FreeBSD 4.9                   gcc 2.95.4
                                  GNU Fortran 0.5.25 
    HP-UX B.11.00                 HP C  HP92453-01 A.11.01.20 
                                  HP F90 v2.4
                                  HP ANSI C++ B3910B A.03.13

    IRIX64 6.5 (64 & n32)         MIPSpro cc 7.3.1.3m
                                  F90 MIPSpro 7.3.1.3m 

    Linux 2.4.20.28               gcc 2.96, GNU Fortran 0.5.25,
                                  Absoft Fortran 9.0
                                  Intel(R) C++ and Fortran Compilers 
                                  Version 8.1
    Linux 2.4.21-268-smp #1 SMP x86_64 (AMD)
                                  gcc 3.3.1
                                  GNU Fortran (GCC) 3.3.1
                                  Intel(R) C++ and Fortran Compilers
                                  Version 8.1
                                  PGI C and Fortran Compilers Version 5.2-1
    Linux 2.4.21-27.0.1.ELsmp #1 SMP
                                  gcc 3.2.3
                                  PGI C and Fortran Compilers Version 5.2-1 

    Linux 2.4.21-sgi303rp05012313_10138 (Altix) 
                                  Intel C++ and Intel Fortran Verison 8.1
    
    Linux 2.4.20-31.9smp_perfctr_lustre (IA-32)
                                  Intel(R) C++ Version 8.0
                                  Intel(R) Fortran Compiler Version 8.0
    Linux 2.4.21.SuSE_241.bef1 (IA-64)
                                  Intel(R) C++ Version 8.0
                                  Intel(R) Fortran Compiler Version 8.0
   
    OSF1 V5.1                     Compaq C V6.5-303 
				  HP Fortran V5.5A-3548
                                  HP Fortran Compiler X5.5A-4085-48E1K

    SunOS 5.7(32 and 64 bit)      WorkShop Compilers 5.0 98/12/15 C 5.0
     (Solaris 2.7)                
                                  WorkShop Compilers 5.0 99/09/16 FORTRAN 77 5.0 patch 107596-03
                                  gcc 3.2.2
                                  g77 GNU Fortran (GCC 3.2.2) 3.2.2 
    SunOS 5.8(32 and 64 bit)      Sun WorkShop 6 update 2 C 5.3
     (Solaris 2.8)                Sun WorkShop 6 update 2 Fortran 77 5.3 

    SunOS 5.9 (32 and 64 bit)     Sun C 5.6 compiler, Sun Fortran 95 8.0

    Windows 2000 (NT5.0)          MSVC++ 6.0
                                  DEC Visual Fortran 6.0
                                  Intel C and F90 compilers version 7.1
    Windows XP                    MSVC++.NET, Intel Fortran 8.1 (static libraries only)
    MAC OS X Darwin 7.7           gcc  3.3
                                  IBM Fortran xlf 8.1
                                  Absoft Fortran 8.2
                                  
                                  

Known problems
==============

o  SZIP Library is not available for Crays SV1 and TS
   Fortran APIs do not support SZIP compression.

o SZIP compression cannot be used with GR interfaces. For more information
  see "HDF4.2r1 SZIP Release Notes" available at 
  http://hdf.ncsa.uiuc.edu/doc_resource/SZIP/SZIP_HDF4_2r1.pdf

o  This release doesn't support VMS system.

o  N-Bit compression is not supported with Fortran APIs.

o  Using both fill-value and compression on SD datasets doesn't work.

o  SDgetdimscale incorrectly returns FAIL and or returns incorrect data
   when the associated SDS has the same name as the dimension.

o  When using PGI compilers make sure that JPEG library is also compiled with 
   PGI C compiler; linking with JPEG built with gcc causes JPEG library tests
   to fail.  To bypass the problem

       x Set LIBS flag to $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a
          where $PGI_JPEG_INSTALL_DIR points to the installtion directory
          for the PGI-compiled JPEG library:

          setenv LIBS $PGI_JPEG_INSTALL_DIR/lib/libjpeg.a

       x Use  --with-jpeg=$PGI_JPEG_INSTALL_DIR
         configure flag to configure with the PGI-compiled JPEG library:

          ./configure --with-jpeg=$PGI_JPEG_INSTALL_DIR --with-zlib....
%%%4.2r0%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


                          HDF 4.2 Release 0
                           December 2003

INTRODUCTION

This document describes the differences between HDF 4.1r5 and
HDF 4.2r0.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.2r0

The HDF 4.2r0 documentation can be found on the NCSA ftp server 
(ftp.ncsa.uiuc.edu) in the directory:

     ftp://hdf.ncsa.uiuc.edu/HDF/Documentation/

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Support for new platforms
- Bugs fixed since HDF4.1r5
- Documentation
- Platforms Tested
- Known problems

New Features and Changes:
========================

o IMPORTANT: HDF4 HAS A NEW CONFIGURATION 

  ZLIB and JPEG libraries were removed from the HDF4 distribution source.
  ZLIB and JPEG have to be installed on the system before HDF4 library
  can be built or HDF4 precompiled binaries can be used.
  Please read INSTALL in the top HDF4 directory for instructions
  how to build the HDF4 library and applications.

o HDF4 has an optional SZIP compression method; in order to use SZIP compression,
  SZIP library has to be installed on the system. Please refer to the INSTALL 
  file for instructions on how to build with/without the SZIP Library.
  SZIP in HDF4 is free for non-commercial use; 
  see http://hdf.ncsa.uiuc.edu/doc_resource/SZIP/Commercial_szip.html 
  for information regarding commercial use. 

  For more information about SZIP compression
  see http://hdf.ncsa.uiuc.edu/doc_resource/SZIP/ and 
  the "HDF4 Reference Manual" entries for the GRsetcompress and 
  SDsetcompress functions. 

o IMPORTANT note about prebuild binaries:

  NCSA precompiled binaries has SZIP compression method enabled for all platforms
  except Crays T3E and SV1 and Linux 2.4 SuSE x86_64. To use the binaries download
  the SZIP library from http://hdf.ncsa.uiuc.edu/doc_resource/SZIP/

o The following new tools have been added

      hrepack
      hdiff
      hdfimport

  See "HDF4 Reference Manual" in the HDF 4.2r0 documentation set for more
  information.

o fp2hdf is removed. It is replaced with hdfimport.

o Helper scripts to facilitate HDF4 installation and compilation were added:
  
      h4cc   - to compile C application with the HDF4 Libraries
      h4fc   - to compiler Fortran applications with the HDF4 Libraries
      h4redeploy - to fix binary installation

  See "HDF4 Reference Manual" in the HDF 4.2r0 documentation set for more
  information.

Support for new platforms 
=========================

o HDF4 was ported to the following platforms

      AIX 5.1 64-bit version
      MacOSX
      Linux 2.4 RH8 and RH9 
      Linux 2.4 RH8 64-bit, SuSE 64-bit
      Linux 2.4 ia64
      Linux 2.4 SGI (Altrix)


Bugs fixed since HDF4.1r5
=========================

1. "hdp dumpgr" and "hdp dumpsds" have two new options:
        -g to suppress the data of global (or file) attributes
        -l to suppress the data of local attributes

2. The problem where hdp failed on a very long file name has been
   fixed. (bug #693)

3. The problem where VSinquire failed when being called on a vdata
   that had no fields defined, has been fixed. (bug #626)

4. When the values of VGNAMELENMAX and VSNAMELENMAX are changed
   the hdp output doesn't reflect the change. This problem is 
   now fixed. (bug #606)

5. hdp dumpvg sometimes failed when reading a file that had a vgroup 
   being inserted into another.  This has been fixed. (bug #477)

6. hdf2gif failed when a user tried it on JPEG compressed images. (Bug #601).
   The problem is now fixed. An error message is displayed if the image is not
   8-bit. If the image is 24-bit, the message suggests using hdf2jpeg.

7. ncdump failed to read NetCDF files 3.5 when there was more than one variable
   with unlimited dimensions. Fixed.

8. The NetCDF part of the HDF4 library was not ported to Compaq True64 system. 
   Fixed.

9. The hdp commands dumpsds, dumpgr, dumpvd, and dumpvg now display an 
    informative message when a non-HDF file is given as input. (Bug #817)

10. The compilation warnings and error on the macro HDFclose are fixed.
    (Bug #818)

Documentation
==============

    Entries for new utilities hdiff, hrepack, hdfimport and helper
    scripts h4cc, h4fc, and h4redeply were added to the Reference Manual.

Platforms Tested
================

HDF 4.2 Release 0 has been tested on the following platforms:

    AIX 5.1  (32 and 64-bit)      xlc 6.0.0.2
                                  xlf 8.1.1
    Cray T3E sn6606 2.0.6.08      Cray Standard C Version 6.6.0.2
                                  Cray Fortran Version 3.6.0.2
    Cray SV1 sn9617 10.0.1.2      Cray Standard C Version 6.6.0.2
                                  Cray Fortran Version 3.6.0.2
    FreeBSD 4.9                   gcc 2.95.4
                                  g++ 2.95.4
    HP-UX B.11.00                 HP C  HP92453-01 A.11.01.20 
                                  HP F90 v2.4
                                  HP ANSI C++ B3910B A.03.13
    IRIX64 6.5 (64 & n32)         MIPSpro cc 7.3.1.3m
                                  F90 MIPSpro 7.3.1.3m 
    Linux 2.4.20-20.7 (RH8)       gcc 3.3.1
                                  Intel(R) C++ Version 7.1
                                  Intel(R) Fortran Compiler Version 7.1
    Linux 2.4.20-20.9 (RH9)       gcc 3.2.2
    Linux 2.4.21-2.9.5ws x86_64   gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-16)
                                  g77 based on gcc version 3.2.3
    Linux 2.4.19-SMP #1 x86_64    gcc version 3.3.2 (SuSE Linux)
                                  g77 version 3.3.2
    OSF1 V5.1                     Compaq C V6.4-014
				  Compaq Fortran V5.5-1877
    SunOS 5.7(32 and 64 bit)      WorkShop Compilers 5.0 98/12/15 C 5.0
     (Solaris 2.7)                WorkShop Compilers 5.0 98/10/25 
                                  FORTRAN 77 5.0
                                  gcc 3.2.2
                                  g77 GNU Fortran (GCC 3.2.2) 3.2.2 
    SunOS 5.8(32 and 64 bit)      Sun WorkShop 6 update 2 C 5.3
     (Solaris 2.8)                Sun WorkShop 6 update 2 Fortran 77 5.3 

    IA-32 Linux 2.4.9-31pctr      Intel(R) C++ Version 7.0
                                  Intel(R) Fortran Compiler Version 7.0
                                  
    IA-64 Linux 2.4.16 ia64       Intel(R) C++ Version 7.0
                                  Intel(R) Fortran Compiler Version 7.0
    IA-64 Linux 2.4.19-SMP        Intel(R) C++  Version 7.1
                                  Intel(R) Fortran Compiler Version 7.1
                                  gcc 3.2
                                  g77 GNU Fortran (GCC 3.2) 3.2
    IA-64 Linux 2.4.21-sgi        Intel(R) C++  Version 7.1
    (Altrix)                      Intel(R) Fortran Compiler Version 7.1
    Windows 2000 (NT5.0)          MSVC++ 6.0
                                  DEC Visual Fortran 6.0
                                  Intel C and F90 compilers version 7.1
    Windows XP                    MSVC++.NET
    MAC OS X                      Darwin 6.8
                                  gcc Apple Computer, Inc. GCC 
                                  version 1175, based on gcc version 3.1
                                  

Known problems
==============

o  SZIP Library is not available for Crays SV1 and T3E
   Fortran APIs do not support SZIP compression.

o  NetCDF tests nctest (C) and ftest (Fortran) fail to read from NetCDF 3.5 files

o  On Linux RH8 64-bit SZIP tests fail if library is compiled in production
   mode. All tests pass in the debug mode.

o  This release doesn't support VMS system.

o  On Linux with gcc compilers Fortran NetCDF APIs cannot read attributes, variables,
   and dimensions when name contain spaces.

o  HDF4 Library cannot be built with PGI compilers.

o  N-Bit compression is not supported with Fortran APIs.

o  Using both fill-value and compression on SD datasets doesn't work.

o  --prefix defines where the installation path is.  This version has
   the default set as /usr/local which is different from previous versions.

o  New utilities hdiff and hrepack are not available for Windows 2000.

%%%4.2r0-Beta%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                          ABOUT HDF 4.2 Release 0-Beta
                               September 2003

INTRODUCTION

This document describes the differences between HDF 4.1r5 and
HDF 4.2r0-Beta.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.2r0-Beta

The HDF 4.2r0-Beta documentation can be found on the NCSA ftp server 
(ftp.ncsa.uiuc.edu) in the directory:

     /HDF/pub/outgoing/hdf4/4.2-Beta/

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested

New Features and Changes:
========================

o ZLIB and JPEG libraries were removed from the HDF4 distribution source.
  Please read INSTALL-4.2r0-Beta in the top HDF4 directory for instructions
  how to build HDF4 Library and applications.

o HDF4 has an optional SZIP compression; please refer to the INSTALL-4.2r0-Beta 
  file for instructions how to build with/without the SZIP Library.
  SZIP in HDF4 is free for non-commercial use; 
  see http://hdf.ncsa.uiuc.edu/doc_resource/SZIP/Commercial_szip.html 
  for information regarding commercial use. 

  For more information about SZIP compression
  see http://hdf.ncsa.uiuc.edu/HDF5/doc_resource/SZIP/ and the "HDF4 Reference Manual"
  entries for the GRsetcompress and SDsetcompress functions. 

o The following new tools have been added

      hrepack
      hdiff
      hdfimport

  See "HDF4 Reference Manual" in the HDF 4.2r0-Beta documentation set for more
  information.

o HDF4 was ported to the following platforms

      AIX 5.1 64-bit version
      MacOSX
      Linux 2.4 RH8 and RH9

Please refer to the bugs_fixed.txt file for more details on bugs that were 
fixed.


Platforms Tested:
================

HDF 4.2 Release 0-Beta has been tested on the following platforms:

   FreeBSD 4.9
   HP-UX B.11.00 
   AIX 5.1 (32 and 64-bit)
   IRIX64 6.5 (-n32, -64)
   Linux 2.4
   Solaris 2.7, 2.8 (32 and 64-bit)
   MacOSX

   No precompiled binaries is available for this release.



%%%4.1r5%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                          ABOUT HDF 4.1 Release 5 
                               November 2001 

INTRODUCTION

This document describes the differences between HDF 4.1r4 and
HDF 4.1r5.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.1r5.

The HDF 4.1r5 documentation can be found on the NCSA ftp server 
(ftp.ncsa.uiuc.edu) in the directory:

     /HDF/HDF/Documentation/HDF4.1r5/

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested

New Features and Changes:
========================

o The following Vdata routines were added:

     VSsetblocksize/vsfsetblsz -- sets the block size of the 
                                  linked-block element.
     VSsetnumblocks/vsfsetnmbl -- sets the number of blocks for 
                                  a linked-block element.
     VSgetblockinfo/vsfgetblinfo -- retrieves the block size and the number 
                                    of blocks of a linked-block element.

o  Two routines were added to get compression information for the SD and
   GR interfaces, including chunked elements: SDgetcompress/sfgcompress 
   and GRgetcompress/mggcompress. 

   Note: 

   - For a JPEG image, GRgetcompress only returns the compression type, not 
     the compression information (i.e, quantity and force_baseline).  This 
     information is not currently retrievable.

   - Getting compression type for JPEG chunked images is not working yet.

o  "hdp dumpgr" has a new option, -pd, to print palette data only.  Also,
   whenever option -p or -pd is given, only palettes are printed, and no 
   images or file attributes. 

o  A new FORTRAN function, heprntf (HEprint), was added.  It takes two
   arguments: file name and level.  If the file name string has 0 length,
   then error messages will be printed to standard output. 

o  On Windows, the unresolved symbol (error_top) error has been fixed when 
   calling HEclear and linking with the DLL.  Users who want to use the HDF 
   DLL should define HDFAPDLL in their applications.  Simply go to Project 
   Settings and add HDFAPDLL as the predefined constant.

o  A memory leak in the netCDF portion of the HDF/mfhdf distribution
   was fixed. 

o  The "#define NULL" was removed since ANSI C compilers are required to
   define NULL.

o  When using "hdp dumpgr", data was being printed in the range of 0-250
   when it should have been between 0-168.  This problem is now fixed.

Please refer to the bugs_fixed.txt file for more details on bugs that were 
fixed.


Platforms Tested:
================

HDF 4.1 Release 5 has been tested on the following platforms:

   Cray SV1 10.0.0.8
   Cray T3E sn6711 2.0.5.55                     
   Compaq Tru64 Unix (OSF1) 5.1
   DEC Alpha/OpenVMS AXP 7.2-1
   FreeBSD 4.4
   HP-UX B.11.00 
   IBM SP 4.3
   IRIX 6.5 
   IRIX64 6.5 (-n32, -64)
   Linux 2.2.18smp
   Solaris 2.7, 2.8
   Windows NT/98/2000

For more information on the platforms that were tested and for
which we provide pre-compiled binaries, please refer to the following
web page (accessible from the HDF home page):

     http://hdf.ncsa.uiuc.edu/platforms.html

Know problmes:

Writing n-bit datasets from FORTRAN with the SD interface is not working.

SDgetchunkinfo does not return compression coding or modelling type.

Using both fill-values and compression on SD datasets is not currently
working, don't use one or the other.

Dumping compressed Vdatas with vshow or hdp is not working.

Reading or writing compressed images with the GR interface is not working.



%%%4.1r4%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                          ABOUT HDF 4.1 Release 4
                                October 2000 

INTRODUCTION

This document describes the differences between HDF 4.1r3 and
HDF 4.1r4.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.1r4.

The HDF 4.1r4 documentation can be found on the NCSA ftp server 
(ftp.ncsa.uiuc.edu) in the directory:

     /HDF/HDF/Documentation/HDF4.1r4/

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested
- Known Problems

New Features and Changes:
========================

This release focuses on new features and changes added to the
GR interface.

o Two new utilities have been added to HDF, gif2hdf and hdf2gif.
  The gif2hdf utility will convert a GIF image into an HDF file
  containing a GR image. The hdf2gif utility will convert an HDF GR 
  image into a GIF image. 
  
o Chunking and chunking with compression have been added to the
  GR interface.

o JPEG compression with the GR interface was not working properly.
  This problem has been fixed.

Several hdp options have been added:
  
o Added -s option to dumpgr and dumpsds to allow printing data 
  as a stream instead of breaking the lines at 65 characters. 

o Added option -c to dumpgr and dumpsds to allow printing clean output 
  for attributes with type DFNT_CHAR. With this option, hdp will print 
  space characters, such as horizontal tabs, CRs, and LFs, as they are 
  instead of "\digit" (still the default.)  This option also prints "..." 
  for one or more null characters among the data.

o Added option -l to dumpgr to allow printing data in different interlace
  modes.


Platforms Tested:
================

HDF 4.1 Release 4 has been tested on the following platforms:

   Cray J90  (available after initial 4.1r4 release)
   Cray T3E                      
   DEC Alpha/Digital Unix
   DEC Alpha/OpenVMS
   Exemplar
   FreeBSD
   HP-UX 
   IRIX 
   IRIX64 (-n32, -64)
   Linux
   Solaris
   Solaris x86
   SP
   Windows NT/98/2000

For more information on the platforms that were tested and for
which we provide pre-compiled binaries, please refer to the following
web page (accessible from the HDF home page):

     http://hdf.ncsa.uiuc.edu/platforms.html


Known Problems:
==============

o The ncgen utility fails on the IBM SP.


%%%4.1r3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                          ABOUT HDF 4.1 Release 3
                               May 7, 1999

INTRODUCTION

This document describes the differences between HDF 4.1r2 and
HDF 4.1r3.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.1r3.
The release notes provide more in-depth information concerning
the topics discussed here.  The HDF 4.1r3 documentation can be
found on the NCSA ftp server (ftp.ncsa.uiuc.edu) in the directory:

     /HDF/HDF/Documentation/HDF4.1r3

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested
- Known Problems
- Acknowledgements

New Features and Changes:
========================

o HDF 4.1r2 was unable to properly read HDF SDSs created with HDF 3.3x.
  It did not read the correct SDS names.  This problem has been fixed.

o Many problems have been fixed with the GR interface, including the
  following:

  - The GR interface can now read compressed files created with the 
    DFR8 and DF24 interfaces, except for those which were compressed 
    with IMCOMP compression.
  
  - The GR interface can read and write images compressed with RLE, 
    GZIP and Skipping Huffman compression methods.

  - Palettes can now be written and read properly with the GR interface.

  - 24-bit raster images can now be read by the GR interface.

o You can now create an SDS with a name up to 256 characters in length.
  The previous limit was 64.

o HDF now supports IJP JPEG version 6b and Gzip version 1.1.3.

o Numerous hdp problems have been fixed, including the following:

  - hdp no longer fails on an HDF file which contains a vdata that no 
    records have been written to.

  - hdp no longer fails on the PC and Mactinosh dumping large SDSs.

  - GR file attributes can now be displayed.

  - A palette can now be dumped with the GR command.

o SDfileinfo no longer returns the wrong number of datasets for old
  files created with the DFSD interface.

o This will be the last release that SunOS 4.1.4 is supported.

Check the ./bugs_fixed.txt for other changes that are not listed
here.

Platforms Tested:
================

HDF 4.1 Release 3 has been tested on the following platforms:

   Cray J90                  
   Cray T90 (CFP, IEEE)         
   Cray T3E                      
   DEC Alpha/Digital Unix
   DEC Alpha/OpenVMS
   DEC Alpha NT
   VAX OpenVMS
   Exemplar
   FreeBSD
   HP-UX 10.2
   IRIX 6.5
   IRIX64 6.5 (-n32, -64)
   Linux
   Macintosh 
   Solaris
   Solaris x86
   SP
   SunOS 4.1.4
   Windows NT/95

For more information on the platforms that were tested and for
which we provide pre-compiled binaries, please refer to the following
web page (accessible from the HDF home page):

     http://hdf.ncsa.uiuc.edu/platforms.html


Known Problems:
==============

o On Alpha OpenVMS version 6.2, the DF.OLB and MFHDF.OLB Libraries 
  should be created with optimization turned off. Otherwise hdftest 
  fails (the sfgichnk function returns incorrect information).

o On VAX Open VMS 6.2, the ncgen utility core dumps and an error occurs
  when reading GR image data with user-defined fill values.

o If you encounter problems building on a platform, please be sure to
  check the INSTALL file at the top of the HDF source tree, in case 
  these problems are documented in section 2.5, Platform-specific Notes.

o On the NT, the hdp utility fails in the debug version when using the 
  list command.

Acknowledgements:
================

Fortner Software LLC ("Fortner") created the reference implementations
for the Macintosh and Windows NT/95 of the HDF 4.1r3 library.  For more 
information, please refer to the macintosh.txt and windows.txt files in 
the ./release_notes/ directory.


%%%4.1r2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                        ABOUT HDF 4.1 Release 2 
                            March 16, 1998

INTRODUCTION

This document describes the differences between HDF 4.1r1 and
HDF 4.1r2.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.1r2.
The release notes provide more in-depth information concerning
the topics discussed here.  The HDF 4.1r2 documentation can be
found on the NCSA ftp server (ftp.ncsa.uiuc.edu) in the directory:

     /HDF/Documentation/HDF4.1r2

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look
at the home page for HDF at:

     http://hdf.ncsa.uiuc.edu/

If you have any questions or comments, please send them to:

     hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested
- Known Problems
- Important Fixes
- Acknowledgements

New Features and Changes:
========================

o Data chunking is now supported with the GR interface.  New routines
  for creating and manipulating chunked GR images have been added.  Please
  refer to the ./release_notes/new_functions.txt file and HDF Reference 
  Manual for information on using chunked GRs.

o In previous releases, many C routines existed for which there were  
  no Fortran counterparts.  With HDF 4.1r2, we have added a Fortran 
  routine for most C routines.  Please check the 
  ./release_notes/new_functions.txt file for a list of the new 
  functions added to HDF.

o This is the first release in which the Java Products (the Java-based
  HDF Viewer (JHV) and the Java HDF interface (JHI)) are incorporated in 
  the HDF release itself.  For information on the Java Products, please
  refer to the HDF home page under Information about HDF
  (http://hdf.ncsa.uiuc.edu/about.html).

o In the SD interface, HDF now defaults to ONLY storing the new version 
  of the dimension representation added in HDF 4.0r1. 

  When the dimension representation was changed in 4.0r1, the HDF library 
  defaulted to include both the new and old dimension representations in 
  an HDF file.  Now, this new dimension representation is stored by default.
  The SDsetdimval_comp function can be used to change the dimension 
  representation stored.
 
  Following is a detailed description of the difference between the
  new and old representations:

    Prior to HDF 4.0r1, a vgroup was used to represent a dimension.  The 
    vgroup had a single field vdata with a class of "DimVal0.0".  The vdata 
    had <dimension size> number of records, with each record having a fake 
    value from 0, 1, 2 ... , (<dimension size> - 1).  The fake values were 
    not really required and took up a large amount of space. For applications 
    that created large one dimensional array datasets, the disk space taken by 
    these fake values almost doubled the size of the HDF file. In order to omit 
    the fake values, the new version for a dimension vdata was implemented.
 
    The new version uses the same structure as the old version.  The
    only differences are that the vdata has only 1 record with a value
    of <dimension size> and that the vdata's class is "DimVal0.1",  to
    distinguish it from the old version.

o Platforms dropped with this release:  Cray Y-MP, T3D, and Linux (a.out)  

o Extensive changes have been made to the Reference Manual and User's
  Guide.  The updated Reference Manual is available with this release.  The
  updated User's Guide will be available in the near future.


Platforms Tested:
================

HDF 4.1 Release 2 has been tested on the following platforms:

   Cray T90 (CFP, IEEE)            IRIX 6.2 
   Cray T3E                        IRIX64 6.4 (-n32, -64)
   DEC Alpha/Digital Unix          Linux (elf) 
   Exemplar                        Solaris  
   FreeBSD                         Solaris x86 
   HP-UX 9.03                      SP2 
   HP-UX 10.2                      SunOS 
   IRIX 5.3                   

** The Windows NT/95, Macintosh, Dec Alpha OpenVMS and VAX OpenVMS 
   releases are not available with this release of HDF4.1r2.  Separate 
   releases for these platforms will be available in the near future. 

For more information on the platforms that were tested and for
which we provide pre-compiled binaries, please refer to the following
web page (accessible from the HDF home page):

     http://hdf.ncsa.uiuc.edu/platforms.html

Known Problems:
==============

o Writing n-bit datasets from FORTRAN with the SD interface is not working.

o SDgetchunkinfo does not return compression coding or modeling type.

o Using both fill-values and compression on SD datasets is not currently
  working; don't use one or the other.

o Dumping compressed Vdatas with vshow or hdp is not working.

o Reading or writing compressed images with the GR interface is not working.

o With the GR interface, you cannot create a raster image without writing data 
  to it.


Important Fixes:
===============

o HDF no longer core dumps when reading a NetCDF file.

o HDF now supports little-endian conversion for VAX and Dec 
  Alpha OpenVMS.

o The problems that occurred on the Cray with HDF 4.1r1 have
  been corrected.

See the ./release_notes/bugs_fixed.txt file for more information
on bugs fixed in this release.

Acknowledgements:
================

Fortner Software LLC ("Fortner") created the reference implementations
for Macintosh and Windows NT/95 of the HDF 4.1r2 library, which will
be available in the near future.  For more information, please refer to 
the macintosh.txt and windows.txt files [in the ./release_notes/ directory]. 
(see above).

==================new_functions.txt==================================

This file contains a list of the new functions added with HDF 4.1r2.
The functions in parenthesis were already present in the HDF library,
and are included for clarity.

C                     FORTRAN                 Description
--------------------------------------------------------------------------------

(SDsetcompress)       sfscompress             compresses SDS

(SDwritechunk)        sfwchnk                 writes the specified chunk of
                                              NUMERIC data to the SDS

(SDwritechunk)        sfwcchnk                writes the specified chunk of
                                              CHARACTER data to the SDS

(SDreadchunk)         sfrchnk                 reads the specified chunk of
                                              NUMERIC data to the SDS

(SDreadchunk)         sfrcchnk                reads the specified chunk of
                                              CHARACTER data to the SDS
 
(SDsetchunk)          sfschnk                 makes the SDS a chunked SDS
 
(SDsetchunkcache)     sfscchnk                sets the maximum number of chunks
                                              to cache
 
(SDgetchunkinfo)      sfgichnk                gets info on SDS

(SDsetblocksize)      sfsblsz                 sets block size 

(SDisrecord)          sfisrcrd                checks if an SDS is unlimited



(GRsetcompress)       mgscompress             compresses raster image

GRsetchunk            mgschnk                 makes a raster image a chunked
                                              raster image

GRgetchunkinfo        mggichnk                gets info on a raster image

GRsetchunkcache       mgscchnk                sets the maximum number of chunks
                                              to cache


(Hgetlibversion)      hglibver                gets version of the HDF Library

(Hgetfileversion)     hgfilver                gets version of the HDF file


Vdeletetagref        vfdtr                    deletes tag/ref pair ( HDF object)
                                              from a vgroup

(VSfindclass)        vsffcls                  finds class with a specified 
                                              name in a vdata

VSdelete             vsfdlte                  deletes a vdata

Vdelete              vdelete                  deletes a vgroup



=====================================================================


%%%4.1r1%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                            ABOUT HDF4.1 Release 1
                              February 21, 1997

INTRODUCTION

This document describes the differences between HDF 4.0r2 and
HDF 4.1r1.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.1r1.
The release notes provide more in-depth information concerning 
the topics discussed here.  The HDF 4.1r1 documentation can be 
found on the NCSA ftp server (ftp.ncsa.uiuc.edu) in the directory:

     /HDF/Documentation/HDF4.1r1

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look 
at the home page for HDF at: 

    http://hdf.ncsa.uiuc.edu/  

If you have any questions or comments, please send them to:

         hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested
- Known Problems
- Important Fixes


New Features and Changes:
========================

o Attributes are now supported in both the vdata and vgroup 
  APIs.  In the vdata API, attributes can be attached to either 
  vdata fields or vdatas; in the vgroup API, attributes can be 
  attached to vgroups.  This new functionality can also be used
  to attach attributes to vdatas and vgroups created by earlier
  versions of the HDF library.  However, the old versions of
  the HDF library cannot read the new version vdatas and vgroups.
  A vdata/vgroup having attributes will become a new version 
  vdata/vgroup.  For more information, please refer to the file 
  ../release_notes/vattr.txt, the man pages for the new functions, 
  and the HDF 4.1 User's Guide.

o Data chunking is now supported in SD scientific data sets.  
  When data chunking is used, an n-dimensional SDS is stored 
  as a series of n-dimensional chunks, improving performance on 
  certain types of partial read operations.

  New routines for creating and manipulating chunked SD 
  scientific data sets have been provided, and two preexisting 
  SD I/O routines, SDreaddata and SDwritedata, have also been 
  modified to work with chunked SDSs.  For more information, please 
  refer to the file ../release_notes/sd_chunk_examples.txt, the man
  page for sd_chunk, and the HDF 4.1 User's Guide.

o Due to certain limitations in the way compressed SDS datasets are stored, 
  data which has been compressed is not completely writable in ways that 
  uncompressed datasets are.  The "rules" for writing to a compressed 
  dataset are as follows:

    (1) Write an entire dataset that is to be compressed.  i.e. build the
        dataset entirely in memory, then write it out with a single call.
 
    (2) Append to a compressed dataset.  i.e. write to a compressed dataset
        that has already been written out by adding to the unlimited
        dimension for that dataset.
 
    (3) For users of HDF 4.1, write to any subset of a compressed dataset
        that is also chunked.  

  Please refer to the HDF 4.1 User's Guide for more information.

o HDF now creates free format FORTRAN include files.  In order to make 
  FORTRAN 90 programs be able to use HDF include files (*.inc), HDF4.1r1 
  creates F90 versions of these files during the 'make' process on UNIX 
  platforms, by replacing 'C' or 'c' in column 1 with '!'.  Continuation 
  lines in hdf.inc have been eliminated. The F90 version files are named 
  as hdf.f90, dffunc.f90 and netcdf.f90.

o Several performance improvements have been added. Test programs on SPARC
  20/Solaris 2.5 show that when creating an hdf file with 2500 3D (10x10x10)
  float32 SDSs, the program execution speed is improved by 2.5 - 4.8 times,
  and SDend is faster by 4.3 - 20 times.

o A new function, SDsetfillmode, has been added.  It can be used to prevent 
  SDwritedata from pre-filling the dataset with a user defined or default 
  fill value, so that better performance can be obtained.

o SGI has changed some compiler default settings in IRIX 6.2.
  We decided to explicitly define the settings of various ABI related
  options.  For the 64 bit OS ("uname -s" returns IRIX64), HDF uses
  "-64 -mips4" code.  For the traditional 32 bit OS ("uname -s" returns
  IRIX), HDF uses "-32 -mips2".  To use n32 mode on IRIX64, HDF uses
  "-n32 -mips3" code.  Note that in the previous release (4.0r2), HDF
  used only "-n32".  In IRIX 6.1 and before, "-n32" defaulted to
  "-mips4" code but in IRIX 6.2, it defaults to mips3 or mips4 code.
  We decided to explicitly set it to "-n32 -mips3".  Therefore,
  applications linking with the HDF library must be compiled with
  the same explicit ABI options.

o This will be the last release that we support the CM5.

  HDF 4.1 Beta 1 USERS ONLY
  -------------------------

o The SD chunking routine names were changed to be more consistent
  with the SD interface. The names of the routines are now in lower
  case, after the two initial "SD" characters.  For example,
  SDwriteChunk() has been changed to SDwritechunk().

o The _HDF_ENTIRE_VDATA variable has been changed to _HDF_VDATA.
  For those users already using it, a macro called _HDF_ENTIRE_VDATA
  has been added, which is defined as _HDF_VDATA.

o You can now create an empty compressed SDS.

  Please refer to the ../release_notes/bugs_fixed.txt file for changes 
  in this release.
 
Platforms Tested:
================

HDF 4.1 Release 1 has been tested on the following platforms:

  CM5 Parallel I/O, 4.1.3_U1
  DEC Alpha/Digital Unix 3.2
  DEC Alpha/OpenVMS AXP 6.2
  DEC VAX OpenVMS 6.2
  Exemplar 9.03
  Free BSD 2.2
  HP-UX 9.03
  HP-UX 10.10
  IRIX 5.3
  IRIX 6.2_64
  IRIX 6.2_n32 
  IRIX 6.4_64
  IRIX 6.4_n32
  Linux A.OUT 1.2.4
  Linux ELF 2.0.27 (C only)
  Macintosh PowerPC (C only) 
  SP2 4.1
  Solaris 2.5
  Solaris_x86 2.5 (C only)
  SunOS 4.1.3
  Windows NT/95 (C only)

Known Problems:
==============

o With the SD interface, you are unable to overwrite
  existing compressed data, that is not stored in
  "chunked" form.  This is due to compression algorithms 
  not being suitable for "local" modifications in a compressed 
  datastream.   

o There are no plans to add the DF24writeref function 
  to the DF24 interface.  This function will be removed
  from the documentation.

Important Fixes:
===============

o If you opened a file in Read Only mode with the SD interface
  (using SDstart), it would create the file if the file did not
  exist.  This no longer occurs.

o HDF 4.0r2 did not recognize JPEG images created by HDF 3.3r4.
  This has been fixed.

See the ../release_notes/bugs_fixed.txt file for more information
on bugs fixed in this release.


%%%4.1b1%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                            ABOUT HDF4.1 Beta 1
                              December 6, 1996

INTRODUCTION

This document describes the differences between HDF 4.0r2 and
HDF 4.1b1.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.1b1.
The release notes provide more in-depth information concerning 
the topics discussed here.  For documentation, please refer
to the HDF 4.0r2 documentation which can be found on the NCSA 
ftp server (ftp.ncsa.uiuc.edu) in the directory 
/HDF/Documentation/HDF4.0r2.

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look 
at the home page for HDF at: 

    http://hdf.ncsa.uiuc.edu/  

If you have any questions or comments, please send them to:

         hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested
- Known Problems
- Important Fixes


New Features and Changes:
-------------------------

o Attributes are now supported in both the vdata and vgroup 
  APIs.  In the vdata API, attributes can be attached to either 
  vdata fields or vdatas; in the vgroup API, attributes can be 
  attached to vgroups.  This new functionality can be used
  to attach attributes to vdatas and vgroups created by earlier
  versions of the HDF library.  However, the old versions of
  the HDF library cannot read the new version vdatas and vgroups.
  A vdata/vgroup having attributes will become a new version 
  vdata/vgroup.  For more information, please refer to the file 
  ../release_notes/vattr.txt, as well as the man pages for the
  new functions.

o Data chunking is now supported in SD scientific data sets.  
  When data chunking is used, an n-dimensional SDS is stored 
  as a series of n-dimensional chunks, improving performance on 
  certain types of partial read operations.

  New routines for creating and manipulating chunked SD 
  scientific data sets have been provided, and two preexisting 
  SD I/O routines, SDreaddata and SDwritedata, have also been 
  modified to work with chunked SDSs.  For more information, please 
  refer to the file ../release_notes/sd_chunk_examples.txt, as
  well as the man page for sd_chunk.

  More information will be included in the HDF 4.1 documentation,
  which will be available with the release of HDF 4.1.  

o Due to certain limitations in the way compressed SDS datasets are stored, 
  data which has been compressed is not completely writable in ways that 
  uncompressed datasets are.  The "rules" for writing to a compressed 
  dataset are as follows:

    (1) Write an entire dataset that is to be compressed.  i.e. build the
        dataset entirely in memory, then write it out with a single call.
 
    (2) Append to a compressed dataset.  i.e. write to a compressed dataset
        that has already been written out by adding to the unlimited
        dimension for that dataset.
 
    (3) For users of HDF 4.1, write to any subset of a compressed dataset
        that is also chunked.  

  Please refer to the ../release_notes/comp_SDS.txt file for more information.

o A new file, ../release_notes/compile.txt, contains instructions on
  compiling applications on the supported platforms.  If you encounter
  problems with it, please let us know at hdfhelp@ncsa.uiuc.edu. 

o SGI has changed some compiler default settings in IRIX 6.2.
  We decided to explicitly define the settings of various ABI related
  options.  For the 64 bit OS ("uname -s" returns IRIX64), HDF uses
  "-64 -mips4" code.  For the traditional 32 bit OS ("uname -s" returns
  IRIX), HDF uses "-32 -mips2".  To use n32 mode on IRIX64, HDF uses
  "-n32 -mips3" code.  Note that in the previous release (4.0r2), HDF
  used only "-n32".  In IRIX 6.1 and before, "-n32" defaulted to
  "-mips4" code but in IRIX 6.2, it defaults to mips3 or mips4 code.
  We decided to explicitly set it to "-n32 -mips3".  Therefore,
  applications linking with the HDF library must be compiled with
  the same explicit ABI options.

Platforms Tested:
-----------------

HDF 4.1b1 has been tested on the following platforms:

  DEC Alpha/Digital Unix 3.2
  DEC Alpha/OpenVMS AXP v6.2
  DEC VAX OpenVMS v6.2
  Free BSD 2.2
  HP-UX 9.03
  IRIX 5.3
  IRIX 6.2_64
  IRIX 6.2_n32 
  Linux ELF 1.2.13 (C only)
  Macintosh PowerPC (C only) (not ready yet)
  SP2 4.1
  Solaris 2.5
  SunOS 4.1.3
  Windows NT/95 (C only)
  YMP 9.0.2asC

Known Problems:
---------------

o With the SD interface, you are unable to overwrite
  existing compressed data, that is not stored in
  "chunked" form.  This is due to compression algorithms 
  not being suitable for "local" modifications in a compressed 
  datastream.  For more information, please refer to 
  the ../release_notes/comp_SDS.txt file. 

o With 4.0r1p1, you could type "hdp list -a <HDF file>
  to get a list of the file attributes associated with
  a file.  This does not currently work.

o There are no plans to add the DF24writeref function 
  to the DF24 interface.  This function will be removed
  from the documentation.

o When running "make test" on OpenVMS, Test 3 (float32) of the 
  chunking tests fails, and has therefore been commented out.

o When running the tests on Window NT/95, Test 2 (uint16) of the
  chunking tests fails, and will be commented out.
 

Important Fixes:
----------------

o If you opened a file in Read Only mode with the SD interface
  (using SDstart), it would create the file if the file did not
  exist.  This no longer occurs.

o HDF 4.0r2 did not recognize JPEG images created by HDF 3.3r4.
  This has been fixed.

See the ../release_notes/bug_fixed.txt file for more information
on bugs fixed in this release.


%%%4.0r2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                            ABOUT HDF4.0 Release 2
                                July 19, 1996

INTRODUCTION

This document describes the differences between HDF 4.0r1p1 and
HDF 4.0r2.  It is written for people who are familiar with
previous releases of HDF and wish to migrate to HDF 4.0r2.
The documentation and release notes provide more in-depth 
information concerning the topics discussed here.  The HDF 4.0
documentation can be found on the NCSA ftp server in the
directory /HDF/Documentation/HDF4.0/Users_Guide.

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look 
at the home page for HDF at: 

    http://hdf.ncsa.uiuc.edu/  

If you have any questions or comments, please send them to:

         hdfhelp@ncsa.uiuc.edu

CONTENTS

- New Features and Changes
- Platforms Tested
- Known Problems


New Features and Changes:
-------------------------

o HDF now supports unlimited number of access IDs and files IDs.

o The vdata field size limit has been increased from 32000 to 65535.

o The hdp utility has been updated to:
   - view a GR object
   - recognize the new compression methods
   - view descriptive annotations
   - display the library version of the HDF file

o SDsetattr and GRsetattr now check for both MAX_ORDER and 
  MAX_FIELD_SIZE.

o The handling of DFNT_CHAR in all Fortran interfaces has been 
  cleaned up.  See release_notes/Fortran_APIs.txt for more 
  information.

o When appending compressed data onto the end of an unlimited
  dimension SDS, the SD interface no longer writes the fill-values
  in locations where they will immediately be over-written by data.
  This was done for the compression layer, but has the added
  enhancement of improving performance.

o On the Cray, there were boundary problems when foreign data did not
  start from the 64-bit boundary.  This has been fixed.

o There are no longer the following name collisions with the HDF 
  libraries:
     -  AVS (HPread, HPwrite)
     -  Windows SDK (_hread) 
     -  ODL library (_HDF_<constant>)

o The 32-bit mode for IRIX 6.1 previously used the '-32' option which
  produces mips1 code.  It has been changed to use '-n32' which
  produces mips4 code.  This runs faster on the Power Challenges.
  Users who must use the '-32' option can link their code with
  the IRIX 5.3 HDF library.

o The compression problems have been fixed when using HDF on IRIX 6.1 
  with the -n32 (see Known Problems below).

o The zlib and jpeg libraries have been updated.  The versions included
  with HDF 4.0 Release 2 are:

      zlib version 1.0.2
      jpeg version 6a (7-Feb-96)
       
o The hdfls utility has been updated to:
    - support the new compression modes
    - display the library version of the HDF file

o Support for the 16-bit architecture has been pulled out of HDF.

o The directories separator in the directory variable used by the
  function HXsetdir (Fortran equivalent: hxsdir) is the verticle bar
  ('|') now.  It used to be the colon (':') symbol, but a colon is
  a legal symbol for a file pathname in the MacOS system.

o The code has been rearranged so that most applications' binaries
  will be smaller.

o A new routine, VSfpack(), has been added.  Please see the HDF man
  page on how to use this routine.

o A new routine, GRluttoref(), has been added.  Please see the HDF man
  page on how to use this routine. 

o Several internal problems have been fixed with the GR interface.


Changes in Compiling the Source Code:

o A new compile option, '-DHAVE_NETCDF', has been added, to avoid conflicts 
  in linking the HDF/MFHDF library with the original netCDF library. 
  This is only available for the C-interface.  However, keep in 
  mind that you cannot read/write HDF files using the netCDF libraries.  
  See section 2.4.3.2 in the INSTALL file for more information.  

o When compiling and installing HDF, the default location to place the
  binaries, has been changed from /usr/local/bin to NewHDF in the
  source directory.  For example, assuming the library source is loaded 
  at /usr/local/src/hdf, the following commands will result in the HDF 
  binaries being placed in the directory /usr/local/src/hdf/dev/NewHDF.

        cd dev
        ./configure -v
        make 
        make test
        make install

o The Fortran test output has been cleaned up and shortened, when 
  running "make test".  Previously, the Fortran tests on the hdf/
  side consisted of multiple Fortran programs invoked by a C frontend.  
  The test programs were changed to subroutines and combined as one 
  Fortran program.  The C frontend was also changed to produce a 
  'directive' file, called fortest.arg, which contains directives to 
  run the Fortran test program.


Platforms Tested:
-----------------

HDF 4.0r2 has been tested on the following platforms:

  AIX                           Linux ELF
  C90                           MAC 
  CM5                           SP2  (single node)
  Digital Unix 3.2              Solaris_2.4
  Exemplar 9.03                 Solaris 2.5
  Free BSD                      Solaris_x86 2.4  (C only)
  Fujitsu  (C only)             SunOS 4.1.4
  HP-UX                         T3D  (C only)
  IRIX 6.1 w/-n32 bit option    VMS
  IRIX 6.1 w/-64 bit option     Windows NT/95
  IRIX 5.3                      YMP
  Linux A.OUT                   


Known Problems:
---------------

o On the SunOS platform, there is a bug when using sfscal()/sfgcal() 
  routines with gcc and f77.
 
o On the VMS platform, there is a bug with float64 data.

o For IRIX 6.1, the stdio.h file gives a false warning message if both 
  the '-n32' and '-ansi' options are used for the C compiler.  We have 
  temporarily removed the '-ansi' option from our autoconfiguration
  for the Irix6_32 system, to avoid these messages.  We have verified
  that the culprit in stdio.h has been corrected in IRIX 6.2, and plan
  to put the '-ansi' option back in our next release.

o The compression tests produce errors for FLOAT32 data if the '-O'
  option is used on IRIX 6.1, for both the '-64' bit and '-n32'
  bit modes.  It did not produce errors when using the '-32' bit 
  option or when not using the '-O' option.  We are unsure whether the 
  errors are due to the compression code or the IRIX C optimizer.  For 
  now, we have chosen to compile the HDF library without the '-O' option, 
  while we investigate the problem. 

%%%4.0r1%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                    ABOUT HDF4.0 Release 1
                       February 7, 1996

INTRODUCTION

This document describes the differences between HDF4.0r1 and
HDF3.3r4.  It is written for people who are familiar with 
previous releases of HDF and wish to migrate to HDF4.0r1.
The documentation and release notes provide more in-depth 
information concerning the topics discussed here.  The HDF 4.0
documentation can be found on the NCSA ftp server in the
directory /HDF/Documentation/HDF4.0/Users_Guide.  For more 
history behind the implementation of the items listed here, 
refer to the ABOUT_4.0.alpha, ABOUT_4.0b1 and ABOUT_4.0b2 files.

First-time HDF users are encouraged to read the FAQ in this
release for more information about HDF.  Users can also look 
at the home page for HDF at: 

    http://hdf.ncsa.uiuc.edu/  

If you have any questions or comments, please send them to:

         hdfhelp@ncsa.uiuc.edu

CONTENTS

- Important Changes (that will affect you) 
- New Features and Changes
- Changes in Utilities
- Known Problems


Important Changes: 
-----------------

  1. Several changes have been made to the libraries in HDF4.0
     which affect the way that users compile and link their
     programs:

      * The mfhdf library has been renamed to libmfhdf.a from 
        libnetcdf.a in previous releases.

      * HDF 4.0 libraries now use v5 of the Independent JPEG Group 
        (IJG) JPEG file access library.

      * Gzip library libz.a is added in HDF4.0r1, in order to 
        support "deflate" style compression of any object in 
        HDF files.

     Due to these changes, users are required to specify four
     libraries when compiling and linking a program:  libmfhdf.a,
     libdf.a, libjpeg.a and libz.a, even if your program
     does not use JPEG or GZIP compression.  For example:

     For C:

        cc -o myprog myprog.c -I<path of include files> \
              <path of libmfhdf.a> <path of libdf.a> \
              <path of libjpeg.a> <path of libz.a>
       or
  
        cc -o myprog myprog.c -I<path of include files> \
              -L<path of libraries> -lmfhdf -ldf -ljpeg -lz

     For FORTRAN:

        f77 -o myprog myprog.f <path of libmfhdf.a> \
              <path of libdf.a> <path of libjpeg.a> \
              <path of libz.a>
       or
   
        f77 -o myprog myprog.f -L<path of libraries> \
              -lmfhdf -ldf  -ljpeg -lz

     NOTE: The order of the libraries is important: libmfhdf.a
           first, then libdf.a, followed by libjpeg.a and libz.a.
     
     This is also discussed in Items 1, 2, and 3 of the New 
     Features and Changes section of this document.

  2. The HDF 4.0 library will ONLY compile with ANSI C compilers.
     See Item 4 in the New Features and Changes section of this
     document for more information.

  3. The HDF library and netCDF library on Unix systems can now be 
     automatically configured and built with one command.  See Item 5 
     in the New Features and Changes section of this document for more
     information.

  4. In HDF 4.0, the FORTRAN programs dffunct.i and constant.i
     have been changed to dffunct.inc and hdf.inc.  See Item 16 in
     the New Features and Changes section of this document for more 
     information.
  
  5. Platforms tested on: IRIX (5.3, 6.1 (32 bit and 64 bit)), 
     SunOS 4.1.4, Solaris (ver 2.4, 2.5), Solaris x86, 
     HP-UX, Digital Unix, AIX, LINUX (A.OUT), CM5, YMP,
     FreeBSD, C90, Exemplar, Open VMS, and SP2 (single node only). 

     HDF 4.0 is not yet available on the Macintosh for HDF4.0r1.

  6. The HDF 4.0 binaries for each tested platform are available. 
     Unix binaries are located in the bin/ directory.  Binaries for 
     Windows NT are located in the zip/ directory. 
     

New Features and Changes:
------------------------

  1. Changes to the mfhdf library
     The mfhdf library has been renamed to libmfhdf.a from libnetcdf.a 
     in previous releases. To link a program with HDF4.0r1
     libraries, four libraries are required:  libmfhdf.a, libdf.a, 
     libjpeg.a and libz.a. 

     See Item 1 of 'Important Changes' for examples of how you would 
     compile and link your programs.

  2. JPEG Group v5b library
     HDF Version 4.0 libraries now use v5 of the Independent 
     JPEG Group (IJG) JPEG file access library.

     The JPEG library will need to be linked with user's 
     applications whether they are compressed with JPEG or not.

     See Item 1 of 'Important Changes' for examples of how you would 
     compile and link your programs.

  3. Gzip library added
     New with this release is support for gzip "deflate" style 
     compression of any object in an HDF file.  This is supported 
     through the standard compression interface function calls 
     (HCcreate, SDsetcompress, GRsetcompress).  The ABOUT_4.0b2 
     file contains additional information on this. 

     See Item 1 of 'Important Changes' for examples of how you would 
     compile and link your programs.

  4. ANSI C only
     As was previously noted in the HDF newsletters, this release 
     of the HDF library will compile only with ANSI C compilers. 
     This shift to ANSI C compliance has been accompanied by a large 
     clean up in the source code. An attempt has been made to remove 
     all warnings and informational messages that the compilers on 
     supported platforms occasionally emit, but this may not be 
     completely clean for all user sites. 

  5. Auto configuration 
     Both the HDF library and netCDF library on Unix systems now use 
     the same configure script and can be configured uniformally with 
     one command. See the README and the INSTALL files at the top 
     level of HDF4.0r1 for detailed instructions on configuration and 
     installation.

     A consequence of the auto configuration is that on UNIX systems 
     without FORTRAN installed, the top level config/mh-<sys> will 
     need to have the 'FC' macros defined to "NONE" for correct 
     configuration. 
     
  6. New version of dimension record
     In HDF4.0b1 and previous releases of the SDS interface, a vgroup 
     was used to represent a dimension.  The vgroup had a single field 
     vdata with a class of "DimVal0.0".  The vdata had <dimension size> 
     number of records, with each record having a fake value from 
     0, 1, 2 ... , (<dimension size> - 1).  The fake values were not 
     really required and took up a large amount of space. For 
     applications that created large one dimensional array datasets, the 
     disk space taken by these fake values almost doubled the size of the 
     HDF file. In order to omit the fake values, a new version of 
     dimension vdata was implemented.

     The new version uses the same structure as the old version.  The 
     only differences are that the vdata has only 1 record with a value
     of <dimension size> and that the vdata's class is "DimVal0.1",  to
     distinguish it from the old version.

     No change was made in unlimited dimensions.

     Functions added to support this are:
     
       - SDsetdimval_comp -- sets backward compatibility mode for a 
         dimension.  The default mode is compatible in HDF4.0r1, and 
         will be incompatible in HDF4.1. See the man page of 
         SDsetdimval_comp(3) for detail.

       - SDisdimval_bwcomp(dimid) -- gets the backward compatibility
         mode of a dimension. See the man page of SDisdimval_bwcomp(3) 
         for detail.

  7. Reading CDF files
     With HDF 4.0 limited support for reading CDF files was added to 
     the library. This support is still somewhat in the development 
     stage and is therefore limited. 

     To begin with, unlike the netCDF merger, the CDF API is not 
     supported. Rather, the SD and netCDF APIs can be used to access 
     information pulled out of CDF files. 

     The type of files supported are limited to CDF 2.X files. The 
     header information is different between CDF 1.X and 2.X files. In 
     addition, all of the files must be stored as single-file CDFs in 
     network encoding. 

     If there is user demand, and support, the types of CDF files 
     that are readable may be increased in the future. 

  8. Parallel I/O interface on CM5 
     An extension using the parallel IO in CM5 has been added to
     the SDS interface. Initial tests have resulted in about
     25 MBytes/second IO throughput using the SDA (Scalable
     Disk Array) file system. The library provides interfaces
     for both C* and CMF programming languages. The ABOUT_4.0.alpha
     file has more information concerning this.

     Users will find some examples in the directory
     mfhdf/CM5/Examples.

     The parallel I/O interface stores scientific datasets in
     external files.  New options have been added to hdfls and
     hdfpack to handle them.  A new utility, hdfunpac, was
     created for external files handling, too. 

  9. Support for SGI Power Challenge running IRIX6.1 
     Power Challenge is now supported, both in the native 64-bit 
     and the 32-bit objects modes.  Note that the Power Challenge 
     native 64 bits objects use 64 bits long integers. Users should
     be careful when using the netcdf interface.  They should declare 
     their variables as "nclong", not "long". 

 10. Multi-file Annotation Interface (ANxxx)
     The multi-file annotation Interface is for accessing 
     file labels and descriptions, and object labels and 
     descriptions. It allows users to keep open more than 
     one file at a time, and to access more than one 
     annotation at a time.  It also allows multiple labels 
     and multiple descriptions to be applied to an HDF object 
     or HDF file. 
   
 11. Multi-file Raster Image (GRxxx) interface
     The new Generic Raster (GR) interface provides a set of 
     functions for manipulating raster images of all kinds.  
     This interface allows users to keep open more than one 
     file at a time, and to "attach" more than one raster 
     image at a time.  It supports a general framework 
     for attributes within the RIS data-model, allowing 
     'name = value' style metadata.  It allows access to 
     subsamples and subsets of images.  
 
     The GRreqlutil and GRreqimageil functions allow for different 
     methods of interlacing images in memory.  The images are 
     interlaced in memory only, and are actually written to disk in 
     "pixel" interlacing.

 12. Compression for HDF SDS
     Two new compression functions have been added to the SD
     interface for HDF 4.0:  SDsetcompress and SDsetnbitdataset.

     SDsetcompress allows users to compress a scientific dataset 
     using any of several compression methods.  Initially three 
     schemes, RLE encoding, an adaptive Huffman compression 
     algorithm,  and  gzip 'deflation' compression are available. 

     SDsetnbitdataset allows for storing a scientific dataset 
     using integers whose size is any number of bits between 1 and 
     32 (instead of being restricted to 8, 16 or 32-bit sizes). 
     Access to the data stored in an n-bit data item is transparent
     to the calling program.  The ABOUT_4.0.alpha file has an in-depth
     description concerning this ("n-bit SDS" listed under Item 2).  

 13. External Path Handling
     New functions have been added to allow applications to 
     specify directories to create or search for external 
     files.  
     
      - HXsetcreatedir (hxscdir for FORTRAN) 
      - HXsetdir (hxsdir for FORTRAN)

 14. I/O performance improvement 
     HDF 4.0 unofficially supports file page buffering.  With HDF 4.1
     it will be officially supported.  The file page buffering allows 
     the file to be mapped to user memory on a per page basis i.e. a 
     memory pool of the file.  With regards to the file system, page 
     sizes can be allocated based on the file system page-size or 
     in a multiple of the file system page-size. This allows for fewer 
     pages to be managed as well as accommodating the user's file usage 
     pattern.  See the top level INSTALL file and the 
     release_notes/page_buf.txt file for creating the library with
     this support and using it.
     
 15. Improvement in memory usage and general optimizations
     Considerable effort was put into this release (since the b2 
     release) to reduce the amount of memory used per file and by the 
     library in general.  In general terms, we believe that the library 
     should have at least half as large of a memory footprint during 
     the course of its execution and is more frugal about allocating 
     large chunks of memory.
 
     Much time was spent optimizing the low-level HDF routines for this 
     release to be faster than they have been in the past also.  
     Applications which make use of files with many (1000+) datasets 
     should notice significant improvements in execution speed.
 
 16. In hdf/ there are two files for FORTRAN programs to include
     the values and functions defined in HDF. They were
     originally named as constant.i and dffunct.i. The extension .i
     caused problems on some machines since *.i is used by cc as
     an "intermediate" file produced by the cpp preprocessor. In
     HDF 4.0 dffunct.i has been changed to dffunct.inc, and constant.i 
     has been changed to hdf.inc. Users' existing FORTRAN application
     programs need to make the corresponding changes, if they
     include the .i files, in order to compile with HDF4.0. 

 17. Limits file
     A new file, limits.txt, has been added to the ftp server.  
     It is aimed at HDF applications programmers and defines the
     upper bounds of HDF 4.0. This information is also found in the
     hdf/src/hlimits.h file.  Refer to the ABOUT_4.0.alpha for 
     historical information concerning this.

 18. Pablo available
     HDF4.0 supports creating an instrumented version of the HDF 
     library(libdf-inst.a). This library, along with the Pablo 
     performance data capture libraries, can be used to gather data 
     about I/O behavior and procedure execution times.  See the top
     level INSTALL file and the hdf/pablo/README.Pablo file for
     further information.

 19. Support for the IBM SP-2 
     The HDF library has been ported to run in a single SP2 node.
     It does not support the parallel or distributed computing for
     multiple SP-2 nodes yet.

 20. Miscellaneous fixes

     - To avoid conflicts with C++, internal structures' fields which
       were named 'new' have been renamed.

     - The maximum number of fields in a vdata now is decided by 
       VSFIELDMAX.

     - The platform number subclass problem when an external data file 
       was in Little_endian format has been fixed.

     - Unlimited dimension was not handled correctly by the HDF3.3r4
       FORTRAN interface.  This problem has been fixed in HDF4.0r1.

Changes to utilities:
--------------------

   o hdf/util/ristosds 
     Ristosds now converts several raster images into a 3D uint8, 
     instead of float32, SDS. 

   o hdf/util/hdfls
     New options have been added to support the parallel I/O
     interface on CM5.

   o hdf/util/hdfpack
     New options have been added to support the parallel I/O
     interface on CM5.

   o hdf/util/hdfunpac
     This is a new utility for external file handling for the
     parallel I/O interface on CM5.

   o mfhdf/dumper/hdp
     Hdp is a new command line utility designed for quick display of 
     contents and data objects.  It can list the contents of hdf files 
     at various levels with different details.  It can also dump the 
     data of one or more specific objects in the file.  See hdp.txt in 
     the release notes for more information.

Known Problems:
--------------

   o On the IRIX4 platform, fp2hdf creates float32 and float64 values
     incorrectly.   

   o On the SP2, the hdp command gives a false message of "Failure to
     allocate space" when the hdf file has no annotations to list. 

   o On the C90, hdfed fails inconsistently when opening hdf files
     more than once in the same hdfed session.

   o Currently there is a problem in re-writing data in the middle
     of compressed objects.
  
   o VMS gives an error on the test for Little Endian float64.

   o If the external element test in hdf/test/testhdf fails
     and there is no subdirectory "testdir" in hdf/test/,
     create one via "mkdir" and run the test again. (The
     "testdir" should have been created by "make". But
     the "make" in some old systems does not support the
     creation commands.)

%%%4.0b2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                ABOUT HDF4.0 Beta 2
                   Nov 14, 1995
 
CONTENTS
 
     1. The mfhdf side library is renamed to libmfhdf.a,
        versus libnetcdf.a in previous releases
     2. New version of dimension record  
     3. New features
        GR interface
        Gzip library is added
        Unified configuration of library
        I/O performance improvement
     4. New functions added
        Fortran functions hxscdir and hxsdir         
        SDsetdimval_comp
        SDisdimval_bwcomp
     5. SGI Power Challenge running IRIX6.1 is now supported
     6. Pablo available  
     7. Platforms tested
     8. Changes in release notes 
     9. Bug fixes and Known problems


1. The mfhdf side library is renamed to libmfhdf.a, versus libnetcdf.a 
   in previous releases. To link a program with HDF4.0b2 libraries, 
   one needs four libraries, libmfhdf.a, libdf.a, libjpeg.a and libz.a 
   (see "Gzip library is added" in item 3 below):

      cc -o myprog myprog.c -I<path of include files> \
            libmfhdf.a libdf.a libjpeg.a libz.a

   Note, the order of the libraries is important.

2. New version of dimension record  
   HDF4.0b1 and previous releases use a vgroup to represent a dimension.
   The vgroup has a single field vdata with class "DimVal0.0".
   The vdata has <dimension size> number of records, each record has a
   fake value from 0, 1, 2 ... , (<dimension size> - 1 ). The fake values
   are not really required and take a lot of space. For applications that
   create large one dimensional array datasets the disk space taken by
   these fake values almost double the size of the HDF file. In order to
   omit the fake values, a new version of dimension vdata is proposed.

   The new version uses the same structure as the old version. The only
   differences are that the vdata has only 1 record with value
   <dimension size> and that the vdata's class is "DimVal0.1" to
   distinguish it from the old version. 

   No change is made in Unlimited dimensions. 
   
   See file dimval.txt in subdirectoy release_notes/ of HDF4.0b2 release
   for our policy on the backward compatibility of this dimension version.

3. New features
   . New with this beta release is the support for different methods of
     interlacing images in memory.  This feature is supported through the 
     GRreqlutil and GRreqimageil functions rescribed in the mf_ris.txt 
     document in this directory.  Please note that the images are 
     interlaced in memory only, all images are actually written to disk 
     in "pixel" interlacing.

   . Gzip library is added
     New with this release is support for gzip "deflate" style compression
     of any object in an HDF file.  This is supported through the standard
     compression interface function calls (HCcreate, SDsetcompress,
     GRsetcompress) by using the COMP_CODE_DEFLATE parameter for the coding
     type.  The comp_info structure has a new member, deflate.level, which
     specifies how much effort to expend trying to compress data.  Values
     for deflate.level must be between 1-9, with 1 being small amounts of
     effort (time) and 9 being maximum effort (most time and compression),
     the default value is 6.
     Currently, due to our use of the gzip "zlib" library for support of
     this feature, users must link with the "libz.a" library produced by
     zlib.  (See item1 above). 

          cc -o myprog myprog.c -I<path of include files> \
                  libmfhdf.a libdf.a libjpeg.a libz.a

     Note, the order of the libraries is important. 

     Also, this method of compression currently has several known bugs 
     when used on a 64-bit architecture (DEC Alpha processors, Cray 
     machines, and SGI Power Challenge machines in 64-bit "mode").

   . Unified configuration of library
     Both sides of the library now use the same configure script and
     can be configured uniformly through one makefile fragment. Please
     see the top-level INSTALL file in the distribution for further 
     details.

   . I/O performance improvement 
     This version of the distribution also has preliminary support for 
     file page buffering. Note that is a *Beta* release and is not 
     supported officially. As such it is is provided as is.
     The file page buffering allows the file to be mapped to user memory on 
     a per page basis i.e a memory pool of the file. With regards to the 
     file system, page sizes can be allocated based on the file system 
     page-size or if the user wants in some multiple of the file system 
     page-size. This allows for fewer pages to be managed along with 
     accommodating the users file usage pattern. Please see the 
     documentation in 'release_notes/page_buf.txt'.
     
     We have also reduced the memory requirements for several of the 
     internal HDF library data structures, for greater efficiency. 

4. Functions added
   . Fortran interface functions added for the set external path features.
     They are hxscdir and hxsdir.  See the man page of HXsetcreatedir(3)
     and HXsetdir(3) for detail.
   . SDsetdimval_comp -- sets backward compatibility mode for a dimension.
     The default mode is compatible in HDF4.0b2, and will be 
     incompatible in HDF4.1. See the man page of SDsetdimval_comp(3)
     for detail. 
   . SDisdimval_bwcomp(dimid) -- gets the backward compatibility mode
     of a dimension. See the man page of SDisdimval_bwcomp(3) for
     detail. 

5. SGI Power Challenge running IRIX6.1 is now supported
   Power Challenge is now supported, both in the native 64-bit and the 
   32-bit objects modes.  Note that the Power Challenge native 64 bits 
   objects use 64 bits long integers, users should be careful when using 
   the netcdf interface.  They should declare their variables as "nclong", 
   not "long".

6. Pablo available  
   This version of the distribution has support to create an 
   instrumented version of the HDF library(libdf-inst.a). This 
   library along the Pablo performance data capture libraries 
   can be used to gather data about I/O behaviour and procedure 
   execution times. Please see the documentation 
   release_notes/Pablo.txt in the distribution for further details.

7. Platforms tested
    HDF4.0b2 has been tested on the following systems:
    SunOS 4.1.3, SunOS 5.3 and 5.4(Solaris 2.3 and 2.4), 
    Linux_a.out, Linux_elf, SGI/IRIX5.2, SGI/IRIX5.3,
    SGI Power Challenge/IRIX6.1 (32- and 64-bit), HP/UX 9.01,
    IBM RS6000/AIX, Cray C90, Cray YMP, DEC alpha/UNIX (OSF), 
    DecStation/MIPSEL (ncdump doesn't work), Free BSD 2.0, 
    Solaris_x86, Convex Exemplar/HPUX, and CM5 parallel I/O. 
    See the INSTALL file at the top level of HDF4.0b2 for more 
    details.

8.  Changes in release notes
    The directory release_notes/ contains writeups for the alpha
    and beta releases of HDF4.0. Those files can be used as temporary
    documents for HDF4.0 before the official documentation is 
    available. 

    Newly added: ABOUT_4.0b2, Pablo.txt, dimval.txt, and page_buf.txt
    Files changed: bug_fixed.txt and parallel_CM5.txt.
    AOUBT_4.0.alpha is also included. 

9. Fixes and Known problems

   Problems fixed:
     . To avoid conflicts with C++, internal structures' fields which
       were named 'new' have been renamed.
     . Maximum number of fields in a vdata now is decided by VSFIELDMAX.
     . Vshow and hdp are fixed. Now they can handle as many fields 
       as defined by VSFIELDMAX.
     . Fixed platform number subclass problem when external data file was
       in Little_endian format. 
     . A file hdf/src/hlimits.h has been added to hold definitions for
       maximum number of open files and other limits. 
     . Miscelianeous fixes
   
   Known problems:
     . Hfidinquire not included in binaries
     . Gzip doesn't work on 64-bit machines.
     . Currently there is a problem in appending data to compressed objects.  
     . Hfidinquire is in the source code, but it is not included in the
       pre-compiled code. If your program uses Hfidinquire, you need to
       re-compile libdf.a. 


%%%4.0b1%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


               ABOUT HDF4.0 Beta 1
                 July 25, 1995

CONTENTS

    1. New features in the HDF4.0 Beta 1 release
    2. Bugs fixed and known problems
    3. Platforms tested
    4. Installation of HDF4.0 Beta 1 on WindowsNT/95
    5. Known problems in compilation, testing and
       installation of HDF4.0b1
    6. Installing without FORTRAN support

1. New features in HDF4.0 Beta 1 release

   o Auto configuration 
     It is now possible to automatically configure and build 
     both the HDF library and netCDF library with one command. 
     See the README and the INSTALL files at the top level of 
     HDF4.0beta1 for detailed instructions on configuring and 
     installation.
     
   o Multi-file Annotation Interface (ANxxx)

     The multi-file annotation Interface is for accessing 
     file labels and descriptions, and object labels and 
     descriptions. It allows users to keep open more than 
     one file at a time, and to access more than one 
     annotation at a time.  It also allows multiple labels 
     and multiple descriptions to be applied to an HDF object 
     or HDF file. 
   
     A draft of the documentation for this interface is in 
            ./mf_anno.txt.

   o Multi-file Raster Image (GRxxx) interface
     The new Generic Raster (GR) interface provides a set of 
     functions for manipulating raster images of all kinds.  
     This interface allows users to keep open more than one 
     file at a time, and to "attach" more than one raster 
     image at a time.  It supports a general framework 
     for attributes within the RIS data-model, allowing 
     'name = value' style metadata.  It allows access to 
     subsamples and subsets of images.  HDF4.0beta1 includes
     a C interface only. The Fortran interface will be available 
     in the next release. 
 
     A draft of the documentation for this interface is in 
            ./mf_ris.txt.

   o New Compression Algorithms and interface
     A new low-level compression interface has been added to 
     HDF which allows any data-object to be compressed 
     using a variety of algorithms.  Currently only two 
     compression algorithms are supported: Run-Length 
     Encoding (RLE) and adaptive Huffman.
  
     A draft of the documentation for this interface is in 
            ./compression.txt

   o JPEG Group v5b library
     HDF Version 4.0 libraries now use v5 of the Independent 
     JPEG Group (IJG) JPEG file access library. For more details
     about JPEG library see
 
            ./JPEG_v5b.txt 

     The JPEG library will need to be linked with a user's 
     applications whether they are compressed with JPEG or not.

     For example on a SUN SPARC, if the .h files are in the 
     directory "incdir", and all libraries are in "libdir,"
     the following command should be used to compile a 
     C program "myprog.c":

     cc -DSUN -DHDF -Iincdir myprog.c libdir/libnetcdf.a \
         libdir/libdf.a  /libdir/libjpeg.a -o myprog

     or

     cc -DSUN -DHDF -Iincdir myprog.c -L libdir -lnetcdf \
         -ldf -ljpeg -o myprog

     Note that the order is important: libnetcdf.a must occur first,
     then libdf.a, and then libjpeg.a.
  
     For FORTRAN programs, use command line:

      f77 -o myprogf myprogf.f libdir/libnetcdf.a \
         libdir/libdf.a libdir/libjpeg.a

    or

      f77 -o myprogf myprogf.f -L libdir -lnetcdf -ldf -ljpeg
  
     Note that the order is important: libnetcdf.a, then libdf.a 
     and then libjpeg.a.
 
   o Compression for HDF SDS (not completely working)
     Work is almost complete on the addition of two
     new compression functions to the SD interface. 

     One function, which still has some known bugs, will 
     allow users to compress a scientific dataset using 
     any of several compression methods.  Initially two 
     schemes,  RLE encoding and an adaptive Huffman 
     compression algorithms, will be available. 

     A second function is available for storing a scientific 
     dataset using integers whose size is any number of bits 
     between 1 and 32 (instead of being restricted to 8, 16 
     or 32-bit sizes). 

     A draft of the documentation for these functions is in
            ./comp_SDS.txt


   o External Path Handling
     New functions have been added to allow applications to 
     specify directories to create or search for external 
     files. More explanation can be found in:
   
            ./external_path.txt.
 
          
   o Parallel I/O for the CM5
     An extension using the parallel I/O facilities on a  CM5 
     has been added to the SDS interface.  Initial tests have 
     resulted in about 25 MBytes/second I/O throughput using the 
     SDA (Scalable Disk Array) file system. The library 
     provides interfaces for both C* and CMF programming
     languages. See:

            ./parallel_CM5.txt for details.


   o HDF dumper
     Hdp is a command line utility designed for quick 
     display of contents and data of HDF3.3 objects, RIS, 
     SDS, Vdata, and Vgroup. It can list the contents of 
     hdf files at various levels with different details. 
     It can also dump the data of one or more specific 
     objects in the file.  See:

            ./hdp.txt for details.

     Currently hdp works on SunOS and LINUX only. 

2. Bugs fixed and known problems

  Several bugs or problems, such as failure in setting 
  and getting scales for unlimited dimensions, missing 
  Fortran version of VSQxxxx functions, failure in 
  defining more than 36 fields in Vdatas, etc. were 
  fixed in this beta release. For more details about
  fixed and un-fixed bugs and problems please see:
  
            ./bug_fixed.txt.

3. HDF4.0 Beta 1 has been tested on the following systems:
SunOS 4.1.3, SunOS 5.3 (Solaris 2.3), Linux, SGI/IRIX5.3, 
SGI Power Challenge/IRIX6.0 (32-bit mode only), HP/UX 9.01, 
IBM RS6000/AIX (C only), C3880/ConvexOS,11.0, CM5, Cray C90,
DEC alpha/OSF (C only), DecStation/MIPSEL (C only), Windows NT,
Free BSD 2.0, and Convex Exemplar/HPUX. See the INSTALL 
file at the top level of HDF4.0b1 for more details.

4. Installing HDF4.0 Beta 1 on Windows NT and Windows 95
Since Windows NT, Windows '95 (Chicago) and Windows 3.1 
(with the Win 32s extensions) all are designed to run 
the same 32-bit code, we have decided to support only 
32-bit libraries and code on the MS-Windows platform.  
To build the HDF, JPEG and netCDF libraries and utilities, 
follow the instructions listed in:

            ./install_winNT.txt. 
   
5. Known problems in compilation,testing and installation
   of HDF4.0b1:

   . On SunOS, tsdmmsf.f in hdf/test/fortest fails
   . On C90, mfhdf/fortran test doesn't configure correctly.
     The adaptive Huffman algorithm does not work right 
     either.  Due to this problem, when running 
     hdf/test/testhdf the test module comp prints out 
     error messages.  
   . On DecStation/MIPSEL, ncdump gives a segmentation fault.
   . The Fortran interface has not been tested on IBM RS6000, 
     DecStation/MIPSEL, and Dec Alpha/OSF because a Fortran 
     compiler is not available on those machines in our group.
   . If the external element test in hdf/test/testhdf fails 
     and there is no subdirectory "testdir" in hdf/test/, 
     create one via "mkdir" and run the test again. (The 
     "testdir" should have been created by "make". But 
     the "make" in some old systems does not support the 
     creation commands.)
   . A bug was found in the "mfhdf.h" file late in the testing
     stage. The error occured in the CM5 parallel I/O 
     extension only. The fix is not included in the source
     release, but it is avalable in the binary release for 
     the CM5 version.  Please retrieve the fix there. 
   . SDsetcompress does not work correctly.
   . Hdp now works on SunOS and LINUX only. Commands dumpsds, 
     dumpvd and dumpvg have different problems on other platforms.
     See mfhdf/dumper/README for more details. 

6. Installing without FORTRAN support:
   . On UNIX systems without a FORTRAN system installed, 
     the config/mh-<sys> will need to have the 'FC' macros 
     defined to "NONE" for correct configuration and the 
     target "allnofortran" should be used to build the 
     distribution, instead of the target "all".


%%%4.0alpha%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

                            ABOUT_4.0.alpha

This file was last updated: November 8, 1994 


INTRODUCTION 

This is a preliminary document describing the differences
between HDF4.0 (Alpha) and HDF3.3r3. It is written for people
who already use HDF3.3r3 or earlier versions and wish to be
HDF4.0 Alpha testers. Special emphasis is given to changes
that might be required in existing code. 

The files ABOUT_3.3r3, ABOUT_3.3r2 and ABOUT_3.3r1 which were 
released along with previous releases contain detailed
descriptions of HDF3.3. Those files can be found in this 
directory. First-time HDF users are encouraged to read the FAQ 
file in directory HDF/ for more information about HDF and where 
to get HDF documentation. 

If you have any questions or comments, please send them to: 

hdfhelp@ncsa.uiuc.edu. 

Contents 

1. Changes in include file names for FORTRAN programs 
2. New features supported by HDF4.0 
      ANSI C only 
      n-bit SDS 
      Reading CDF files 
      Parallel I/O interface on CM5 
      Installing HDF Libraries With CM5 Parallel IO Extension 
3. Changes in HDF utilities 
      hdp -- HDF dumper 
      ristosds 
      hdfls 
      hdfpack 
      hdfunpac 
4. Platforms tested 
5. Limits of the current release 

1. Changes in include file names for FORTRAN programs

   In hdf/ there are two files for FORTRAN programs to include
   the values and functions defined in HDF. They were
   originally named as constant.i and dffunct.i. The extension .i
   causes problems on some machines since *.i is used by cc as
   an "intermediate" file produced by the cpp preprocessor. In
   HDF 4.0 dffunct.i is changed to dffunct.inc, and constant.i is
   changed to hdf.inc. Users' existing FORTRAN application
   programs need to make the corresponding changes, if they
   include the .i files, in order to compile with HDF4.0. 

2. New Features supported by HDF4.0

   ANSI C only

      As previously noted in the HDF newsletters, the next
      major release of the HDF library will compile only with
      ANSI C compilers. Backward compatibility will be
      provided through an ANSI->K&R filter which will need to
      be run on each source file in order to convert the ANSI
      style code into K&R style code. Currently the entire HDF
      library has been converted to ANSI code, but the filter
      is not yet in place. Future alpha releases may have the
      code filter in place, but it will definitely be in place
      for the first beta release. This shift to ANSI C
      compliance has been accompanied by a large cleanup in
      the source code. An attempt has been made to remove all
      warnings and informational messages that the compilers
      on supported platforms occasionally emit, but this may
      not be completely clean for all user sites. 

   n-bit SDS

      Support for n-bit integer data has been incorporated
      into this release of the HDF library. The n-bit support
      is currently incorporated into the call to
      SDsetnbitdataset, future releases may incorporate high
      level access through the DFSD interface also. Access to
      the data stored in an n-bit data item is transparent to
      the calling program. 

      For example to store an unsigned 12-bit integer (which
      is represented unpacked in memory as an unsigned 16-bit
      integer), with no sign extension or bit filling and
      which starts at bit 14 (counting from the right with bit
      zero being the lowest) the following setup & call would
      be appropriate: 

      intn sign_ext = FALSE; 

      intn fill_one = FALSE; 

      intn start_bit= 14; 

      intn bit_len = 12; 

      SDsetnbitdataset(sds_id,start_bit,bit_len,sign_ext,fill_one); 

      Further reads and writes to this dataset would
      transparently convert the 16-bit unsigned integers from
      memory into 12-bit unsigned integers stored on disk. The
      corresponding FORTRAN function name is sfsnbit which
      takes the same parameters in the same order.

      A breakdown of the parameters to the SDsetnbitdataset
      call is as follows: 

      int32 sds_id - The id of a scientific dataset returned from
      SDcreate or SDselect. intn start_bit - This value
      determines the bit position of the highest end of the
      n-bit data to write out. Bits in all number- types are
      counted from the right starting with 0. For example, in
      the following bit data, "01111011", bits 2 and 7 are set
      to 0 and all the other bits are set to one. 

      intn bit_len - The number of bits in the n-bit data to
      write, including the starting bit, counting towards the
      right (i.e. lower bit numbers). For example, starting at
      bit 5 and writing 4 bits from the following bit data,
      "01111011", would write out the bit data, "1110", to the
      dataset on disk. 

      intn sign_ext - Whether to use the top bit of the n-bit
      data to sign-extend to the highest bit in the memory
      representation of of the data. For example, if 9-bit
      signed integer data is being extracted from bits 17-25
      (nt=DFNT_INT32, start_bit=25, bit_len=9, see below for
      full information about start_bit & bit_len parameters)
      and the bit in position 25 is a 1, then when the data is
      read back in from the disk, bits 26-31 will be set to a
      1, otherwise bit 25 will be a zero and bits 26-31 will
      be set to 0. This bit-filling takes higher precendence
      (i.e. is performed after) the fill_one (see below)
      bit-filling. 

      intn fill_one - Whether to fill the "background" bits with
      1's or 0's. The "background" bits of a n-bit dataset are
      those bits in the in-memory representation which fall
      outside of the actuall n-bit field stored on disk. For
      example, if 5 bits of an unsigned 16-bit integer
      (in-memory) dataset located in bits 5-9 are written to
      disk with the fill_one parameter set to TRUE (or 1),
      then when the data is read back into memory at a future
      time, bits 0-4 and 10-15 would be set to 1. If the same
      5-bit data was written with a fill_one value of FALSE
      (or 0), then bits 0-4 and 10-15 would be set to 0. This
      setting has a lower precedence (i.e. is performed first)
      than the sign_ext setting. For example, using the
      sign_ext example above, bits 0-16 and 26-31 will first
      be set to either 1 or 0 based on the fill_one parameter,
      and then bits 26-31 will be set to 1 or 0 based on
      bit-25's value. 

   Reading CDF files

      With HDF 4.0 limited support for reading CDF files was
      added to the library. This support is still somewhat in
      the development stage and is therefore limited. 

      To begin with, unlike the netCDF merger, the CDF API is
      not supported. Rather, the SD and netCDF APIs can be
      used to access information pulled out of CDF files. 

      The type of files supported are limited to CDF 2.X
      files. The header information is different between CDF
      1.X and 2.X files. In addition, all of the files must be
      stored as single-file CDFs in network encoding. 

      If there is user demand, and support, the types of CDF
      files readable may be increased in the future. 

   Parallel I/O interface on CM5 

      An extension using the parallel IO in CM5 is added to
      the SDS interface. Initial tests have resulted in about
      25 MBytes/second IO throughput using the SDA (Scalable
      Disk Array) file system. The library provides interfaces
      for both C* and CMF programming languages. Read the
      section "Installing HDF Libraries With CM5 Parallel IO
      Extension" below for specific installation instructions.

      Users will find some examples in the directory
      mfhdf/CM5/Examples. Please send comments, bugs reports,
      etc. to acheng@ncsa.uiuc.edu. 

      The parallel I/O interface stores scientific datasets in
      external files. New options have been added to hdfls and
      hdfpack to handle them. A new utility program, hdfunpac,
      is created for external files handling too. See the man
      pages for details. 

   Installing HDF Libraries With CM5 Parallel IO Extension

      The current alpha version requires two major steps to
      install the HDF libraries (libdf.a and libnetcdf.a). Works
      are in progress to make it simpler in the production
      release. Bear with us for now. 

      1) Compile and install the ordinary HDF libraries,
      include files and utilities according to the
      instructions for a Sun Microsystem machine. 

      2) To make the HDF library with CM5 parallel IO
      extension: There are two new libraries, libdfcm5.a and
      libnetcdfcm5.a that are similar to libdf.a and
      libnetcdf.a. 

      For libdf.a 

              cd hdf
              cp MAKE.CM5 Makefile
              cp src/Makefile.CM5 src/Makefile
              make libdf          # create the parallel IO libdf.a
               # to install it in /usr/local/lib
              cp src/libdf.a /usr/local/lib/libdfcm5.a
              ranlib /usr/local/lib/libdfcm5.a
           

      For libnetcdf.a 

              cd mfhdf
              # edit CUSTOMIZE to use "gcc" as the CC compiler
              # and add "-DCM5" to the CFLAGS variable.
              ./configure
              (cd libsrc; make )      # compile the library
              # to install it in /usr/local/lib
              cp libsrc/libnetcdf.a /usr/local/lib/libnetcdfcm5.a
              ranlib /usr/local/lib/libnetcdfcm5.a
           

3. Changes in HDF utilities

   hdp -- HDF dumper 
      A new utility hdp is under development to list contents
      of HDF files and to dump data of HDF objects. A
      prototype is included in HDF4.0 Alpha for users to play
      with and comment on. Development will continue based on
      users' feedback. More information is contained in
      HDF/HDF4.0.alpha/mfhdf/dumper/README. 

   ristosds 
      Ristosds now converts several raster images into a 3D
      uint8, instead of float32, SDS. 

   hdfls 
      New options to recognize external elements. 

   hdfpack 
      New options to pack external elements back into the main
      file. 

   hdfunpac 
      New utility program to unpack scientific datasets to
      external elements. Can be used to prepare for CM5
      parallel IO access. 

4. HDF 4.0 Alpha has been tested on the following machines

   Platform                'base library'              HDF/netCDF
   ---------------------------------------------------------------
   Sun4/SunOs                    X                         X
   Sun4/SOLARIS                  X                         X
   IBM/RS6000                    X                         X
   SGI/IRIX4                     X                         X
   Convex/ConvexOS *             X                         X
   Cray Y-MP/UNICOS              X                         X
   Cray/C90                      X                         X
   NeXT/NeXTSTEP                 X                         X
   HP/UX 9.01                    X                         X
   DecStation/MIPSEL             X                         X
   IBM PC - MSDOS               **                        ***
   IBM PC - Windows 3.1         **                        ***
   IBM PC - Windows NT           X                         X
   DEC Alpha/OSF                 X                         X
   CM5/                          X                         X

   Fujitsu VP/UXPM               X
   Intel i860                    X
   Mac/MacOS 
   VMS

    * When compiling the mfhdf section of the library on a Convex3 you will
      need to set the environment variable 'MACHINE' to 'c3' before running
      the configure script.

    ** There is no FORTRAN support for either PC version of HDF4.0 Alpha

    *** The netCDF half of the HDF/netCDF merger is not working correctly,
         but the multi-file SD interface is working correctly.

5. Limits of the current release

   Sometimes it is important for HDF users to be aware of
   certain limits in using HDF files and HDF libraries. This
   section is aimed at HDF applications programmers and
   reflects upperbounds as of HDF 4.0. 

   Limits that are #define'd are fully capitalized and the
   file where the symbol is defined is given in parentheses at
   the end of the sentence. If the #define's are changed in
   order to meet the needs of an application, it is important
   to make sure that all other users, who would share the HDF
   library and the hdf files of the application, are aware of
   the changes. 

   If a limit has no #define, the size of the maximum storage
   allocated for that item is given; it would, generally,
   require a large amount of modification of the HDF library
   to change. 

   If a limit is listed as a number type (e.g. int16) then it
   refers to the largest number that can be represented using
   that type. That is: 

           int16 -- 32,767
           int32 -- 2,147,483,647.

   H-Level Limits
   --------------

      MAX_FILE files open at a single time (hfile.h) 
      MAX_ACC access records open at a single time (hfile.h) 
      int16 total tags (fixed) 
      int32 max length and offset of an element in an HDF file (fixed) 

   Vgroup Limits
   -------------
      MAX_VFILE vset files open at a single time (hdf.h)
      int16 elements in a Vgroup (fixed) 
      VGNAMELENMAX max length of a Vgroup name or class (vg.h) 

   Vdata Limits
   ------------
      MAX_VFILE vset files open at a single time (hdf.h)
      VSFIELDMAX fields in a Vdata (hdf.h) 
      FIELDNAMELENMAX characters in a single field name (hdf.h) 
      MAX_ORDER max field order in a Vdata (hdf.h) 
      VSNAMELENMAX max length of a Vdata name or class (hdf.h) 
      int16 max width in bytes of a Vdata record. (fixed) 
      Vdatas can have a maximum field width of MAX_FIELD_SIZE bytes. (hdf.h)
           
   Raster Images
   -------------
      int32 width or height of a raster image. (fixed) 

   SD Limits
   ---------
      MAX_VAR_DIMS dimensions per dataset (defined in netcdf.h
          included by mfhdf.h) 
      int32 maximum dimension length (fixed) 
      MAX_NC_ATTRS attributes for a given object (defined in netcdf.h 
          included by mfhdf.h) 
      MAX_NC_NAME maximum length of a name of a dataset 
          (defined in netcdf.h included by mfhdf.h) 

   Other Convensions / Issues
   --------------------------
      Some utility programs (e.g. ncgen) expect dataset names to be 
      composed of only alphanumeric, '-' and '_' characters. 

