Mscgen is a small program that parses Message Sequence Chart descriptions and
produces PNG, EPS, SVG or server side image maps (ismaps) as the
output. Message Sequence Charts (MSCs) are a way of representing entities and
interactions over some time period and are often used in combination with SDL.
MSCs are popular in Telecoms to specify how protocols operate although MSCs
need not be complicated to create or use. Mscgen aims to provide a simple text
language that is clear to create, edit and understand, which can also be
transformed into images.