  is the ID of the first vertex to be fetched from the
                  segment designated by `handle' and `dladsc'. The ID
                  of a vertex is its ordinal position within the
                  segment. Vertex IDs range from 1 to NV, where NV is
                  the number of vertices in the segment.
 
                  Note that Fortran-style 1-based indexing is used for
                  vertex IDs because these IDs must be consistent with
                  the IDs used in DSK files, across