Example 1.  Creating and Accessing HDF Files and Vdatas

This example illustrates the use of Hopen/hopen, Vstart/vfstart,
VSattach/vsfatch, VSdetach/vsfdtch, Vend/vfend, and Hclose/hclose
to create and to access different vdatas from different HDF files.

The program creates an HDF file, named "General_Vdatas.hdf", and a vdata
stored in this file.  The program also creates another HDF file, named
"Two_Vdatas.hdf", and two vdatas stored in this second file.  Note
that, in this example, the program does not write data to these
vdatas.  Also note that before closing the file, the access to its
vdatas and its corresponding VS interface must be terminated.