I brought this up on python-ideas, but I think discussing it here may be better: I think we may need to use a data file format that has an open source implementation. The tool Yahya used (plantuml) doesn't appear to be open source, which is a problem for the long-term maintainability of the diagram. If I'm wrong about open source tools for reading .puml files to generate SVG files then my worries are alleviated, but if there aren't any then something like a dot file may be better long-term.