What Content is Included in the SRD, and What Does That Mean?
If you're thinking about creating a gaming system along the lines of Dungeons and Dragons, you're going to need to understand the terms of the Open Gaming License, and the System Reference Document.
What is the SRD? What is Pathfinder SRD?
When original creative material is brought into existence, such as a Dungeons and Dragons rules book, it is copyrighted. Wizards of the Coast created the Open Gaming License which basically gives up those rights to some of that material, which is all included for use, modification and distribution, in the System Reference Document.
The System Reference Document is a repository for all things that were created by Wizards of the Coast that are available to use, royalty free. Items in the SRD include but are not limited to content such as core races and classes, and mechanics like feats and skills.
Under the OGL, these things can be used, reprinted, and even modified.
Currently, when someone is talking about the SRD, they're most often talking about the v3.5. There is an SRD for 4e available here in PDF format, but it's much more vague and does not include a whole lot of content.
Who is Publishing Using the SRD?
There is no shortage of content currently being published under the Open Gaming License and using the System Reference Document, including Wizards of the Coast themselves. The System Reference Document is basically the framework that all Wizards of the Coast pen and paper role-playing games use, like D20 Modern, and D20 Future.
Other role-playing games using the system reference document are Mutants and Masterminds by Green Ronin Publishing, Labyrinth Lord by Goblinoid Games, and FATE (which is not based on the d20 system) by Evil Hat Publishing.
Also, one of the most popular systems published thusly is the Pathfinder RPG, published by Piazo Games.
What's Not Included in the SRD?
On the surface, it almost seems like Wizards of the Coast left their entire toolbox open and invited everyone to come in and use it! However, there are some things left noticeably out of the Open Gaming content, and thus do not exist in the System Reference Document.
For example, the following creatures were left out of the SRD because they are considered "Product Identity" by Wizards of the Coast: Beholder, Carrion Crawler, Displacer Beast, Gauth, Githyanki, Gythzerai, Kuo-toa, Mind Flayer, Slaad, Umber Hulk, and Yuan-ti.
Also, many aspects of the Dungeons and Dragons setting called Greyhawk are also omitted from the OGL.
Ok, Where do I Find the SRD?
Obviously, since the System Reference Document is a product of Wizards of the coast, it can be obtained via their website. It can be downloaded section by section in small Rich Text Form (RTF) files, or you can download the whole thing in one 2.2MB Zip file.
There are also other sources around the internet including The Hypertext d20 SRD where you can download more Open Gaming content, and systemreferences.org where you can download card games, board games, and pen and paper games for free.
If you're clear on how the SRD works, but don't quite understand why it was created, or the Open Gaming movement in general, you are not alone! For a better idea of the theory behind it, read this article.
If you've got questions or comments regarding the information provided in this article, or just regarding the Open Gaming License or System Reference Documents, please post in the comments below!