Example 8. Reading from an SDS.

This example uses the routine SDreaddata/sfrdata to read the data that has
been written in Example 2, modified in Example 4, and moved to the external
file in the Example 7. Note that the original file SDS.hdf that contains
the SDS metadata and the external file ExternalSDS that contains the SDS
raw data should reside in the same directory. The fact that raw data is in
the external file is transparent to the user's program.