From HDF's manpage:

       hdf - Hierarchical Data Format library

Description:
       HDF  is	a  multi-object  file format that facilitates the
       transfer of  various  types  of	scientific  data  between
       machines  and  operating systems.  Machines currently sup-
       ported  include	the  Cray,  Convex,  HP,  Vax,	Sun,  IBM
       RS/6000,  Silicon  Graphics, Macintosh, and IBM PC comput-
       ers.  HDF allows self-definitions of data content and easy
       extensibility  for  future  enhancements  or compatibility
       with other standard formats. HDF includes  Fortran  and	C
       calling	interfaces,and	utilities to prepare raw image of
       data files or for use with other NCSA software.	 The  HDF
       library	contains  interfaces  for  storing and retrieving
       compressed or uncompressed 8-bit and 24-bit raster  images
       with   palettes,  n-Dimensional	scientific  datasets  and
       binary tables. An interface is also included  that  allows
       arbitray grouping of other HDF objects.

WWW: http://www.hdfgroup.org/products/hdf4/