Package seqdiag

http://blockdiag.com/

seqdiag and its family generate diagram images from simply text file.

Features:
- Generates beautiful diagram images from simple text format (similar to
  graphviz’s DOT format)
- Layouts diagram elements automatically
- Embeds to many documentations; Sphinx, Trac, Redmine and some wikis

- Supports many types of diagrams
  - sequence diagram (with this package)
  - block diagram (with the blockdiag package)
  - activity diagram (with the actdiag package)
  - logical network diagram (with the nwdiag package)

Enjoy documentation with seqdiag !