In this chapter we describe an actual implementation of the constructive proof of the completion result of Chapter 4. The corresponding software code, a free software program, called visible, is written in C language. It is hosted on sourceforge.net, its home page is http://appcontour.sourceforge.net/, from where the source code can be downloaded, compiled and installed following the standard procedure for Unix projects.
The software basically works as a filter that takes a description of the visible contour graph (briefly, visible contour) K as input and produces a description of a possible completion G as output.
Both input (visible contour) and output (complete labelled contour graph) are described in terms of their topological structure, by using a Morse-like description.
