Example 3. Obtaining Annotation Information

This example illustrates the use of ANnumann/afnumann to obtain the number of
annotations of an object, ANannlist/afannlist to obtain the list of annotation
identifiers, and ANid2tagref/afidtagref, ANatype2tag/afatypetag,
and ANtag2atype/aftagatype to perform some identifier conversions.

In this example, the program locates the vgroup named "AN Vgroup" that
was created in the file "General_HDFobjects.hdf" by Example 1.
The program then gets the number of data descriptions that this
vgroup has and the list of their identifiers.  If there are any identifers
in the list, the program displays the corresponding reference numbers.
Finally, the program makes two simple conversions, from an annotation
type to a tag and from a tag to an annotation type, and displays the
results.