HDF_DFAN_PUTDESC procedure writes a
description for the given tag and reference number in a Hierarchical Data Format file.
Filename, Tag, Ref, Description
A scalar string containing the name of the file to be written.
The reference number.
A string or array of bytes containing the information to be written.
If a description does not exist, the
variable will contain either a 0L (long-integer zero) or a blank string, and a warning message will be printed. Warning messages can be suppressed by setting the !QUIET system variable to a non-zero value.
Attempting to overwrite an existing description with a longer one fails.
Overwriting an existing description with a shorter description succeeds, but the description length is unchanged and garbage characters are left at the end of the description).