The Adventure Guide’s Handbook: Open Source License

Because I’ve released Gods & Monsters under the GNU Free Documentation License, you can use it as you wish—within the constraints of the license. You can, for example, create custom versions of the rulebook or Lore books to hand out to the other players, and you can even make these available on the Internet for people to download. Your custom versions must also be released under the FDL.

You can make your custom versions most easily from the HTML version or the Rich Text Format version. Most word processors (and all good ones) read and write RTF.

Part of your responsibility if you release a document under the FDL is to ensure that an editable version is available for those who wish to make customized versions of your document. The FDL calls these “transparent” copies. Transparent means not only that the format is easily editable today, but that it be easily editable in the future. The FDL describes what constitutes a transparent format. Try to think long-term. Some formats that are easily readable today, such as RTF, can (and probably will) be modified on the whim of a single company. While RTF is a good format to release in today, you should also release in a more standard, simpler format for long-term editability. HTML (simple HTML) is a good choice, and the FDL mentions others.

This is not to say that you are not allowed to release in “opaque” formats. The more formats the merrier! But at least one of them must be editable in the long term.