The VCG description as created is more complex than it need be. VCG allows graphs and nested subgraphs: each subroutine is created as a subgraph nested inside its calling routines. This allows you to interactively display subgraphs or summarise them.
The -vcg option for ftnchek was written by Dr. Philip Rubini of Cranfield University, UK.
xvcg is a graph visualisation tool which runs under the X windows system. It is freely available from ftp.cs.uni-sb.de. It was written by G. Sander of the University of Saarland, Germany.
See also: -calltree, -crossref, -reference, -sort.