Just recently added some new free shapes for drawing MASCOT diagrams. Here is an article about what MASCOT is for:
http://en.wikipedia.org/wiki/Modular_Approach_to_Software_Construction_Operation_and_Test (http://en.wikipedia.org/wiki/Modular_Approach_to_Software_Construction_Operation_and_Test)
and here are the shapes:
http://www.paulherber.co.uk/articles/visio-articles/MASCOT/ (http://www.paulherber.co.uk/articles/visio-articles/MASCOT/)