The Sigil said:[You may reprint anything] published under the OGL/d20 licence that is strictly rules-related published by any company other than WotC (because part of the Open Game License explicitly states that all game mechanics are automatically Open Game Content).
)"Open Game Content" means the game mechanic and includes the methods, procedures, processes and routines to the extent such content does not embody the Product Identity and is an enhancement over the prior art and any additional content clearly identified as Open Game Content by the Contributor, and means any work covered by this License, including translations and derivative works under copyright law, but specifically excludes Product Identity.