From BrWiki
 D20
|
This article is a D20 reference page
The System Reference Document is a comprehensive toolbox consisting of rules, races, classes, feats, skills, various systems, spells, magic items, and monsters compatible with the d20 System version of Dungeons & Dragons and various other roleplaying games from Wizards of the Coast.
|  D20
|
The d20 System is the game engine used in Wizards of the Coast's hobby roleplaying games. The d20 System was used as the root of the System Reference Document (SRD), an abstract version of the rules and nonrule content of the various d20 System roleplaying games from Wizards.
The System Reference Document is a comprehensive toolbox consisting of rules, races, classes, feats, skills, various systems, spells, magic items, and monsters compatible with the d20 System version of Dungeons & Dragons and various other roleplaying games from Wizards of the Coast. You may consider this material Open Game Content under the Open Game License, and may use, modify, and distribute it.
- More information on D20 and the 3.5 SRD, see the official Website
[edit] D20 and Birthright
The version of Birthright developed for the BRCS is designed to be fully compatible with Dungeons & Dragons Edition 3.5, which is based around the d20 system.