Storyteller Hero
Adventurer
Incredibly bad advice.
1.) 4E was not released under the OGL.
2.) That linked sample has no OGL attached to it and even at a glance makes obvious errors that wouldn't be allowed under the OGL like using the term Dungeon Master, etc.
3.) We have no idea if the supplement whence that sample came is under license of any kind.
4.) The OGL has specific language about compatibility claims.
5.) For some time, Kenzer had a special legal situation (perhaps a license) that allowed them to do things in relation to D&D that no other company could based on, from my understanding, the use of some of their IP.
All in all I would avoid any advice that suggests you should follow your understanding of the example of another in a legal matter, just doing what they do, as there are any number of ways in which that is horrible advice. In this case I have pointed out five with only a glance.
Actually the point was that one can state compatibility with another product without a license. Kenzer made a big hubbub about it back in the day.
To quote:
"Correct, we no longer have an agreement with Wizards. Why? Is there some "magic" restriction in IP law that restricts people from making new creative material that doesn't use any TMs, patents or copyrights of another company?
Oh, perhaps it's the magical FUD rule that you're referring to?
By-the-by, KoK first appeared in 1994 and we had no formal relationship with TSR."
"that is not copyright infringement.
copyright infringement is basing your work on someone else's creative expression. Rules are not creative expression. Also, it is not "based" on their rules. It happens to "work with" their rules.
SHould every programmer that writes a program that works with a computer have to pay the owner of the OS it runs on? I think not. I could be wrong, but fortunately, the US and International copyright laws agree with me.
A world where one could not reference others' materials in their product would be a dark and sad place."
http://www.kenzerco.com/forums/showthread.php?38336-Kalamar-4th-Edition&p=678175#post678175
Considering the fact that there was no litigation from WotC, no take-down notices, etc., and the laws themselves one can read from the official Copyright Office site, it's doable.
Just don't do it under the OGL - this also means no direct copy-paste or trademarks. You can use the same rules mechanics under different wording than that which is copyrighted. You can't use copyrighted fluff such as illithid or drow.