From B2evolution

[edit] Source code documentation

Technical documentation, generated from the source code (phpdoc style), is available at http://doc.b2evolution.net/ for CVS HEAD (current development version) and all relevant branches (currently 0.9.x, 1.8 and 1.9).

[edit] Database schema

Graphics of the (approximate) database schema are available at: http://doc.b2evolution.net/DB_schema/