Msc-generator
Draws signalling charts, block diagrams and graphs from text input.
...Currently, three types of charts are supported: Message Sequence Charts, generic Graphs, and Block Diagrams, with more to be added in the future. There is a command-line version for Linux and Mac (replacing mscgen), which now sports a GUI, as well.
Msc-generator allows fine control over the appearance and has a rich feature set complete with detailed documentation. On Windows, you can embed the charts in a document or presentation and simply double-click it in Office to edit them. On Linux and the Mac, a command-line version is available, and a GUI, as well.
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