hi all.
I just want to know, if there is an other documentation on ARB functions, and extension of opengl than the one provide on the sgi site under the form of .txt. I found those .txt pretty hard to understand.
Thanks in advance
Unfortunately, the txt files are the ones most of us read.
There is a book about extensions, even though I haven’t read the book yet.
ok, thanks for help
now i just have to read and read again those txt 
'till i understand them
The body of an extension spec is written against a version of the core OpenGL specification (it’s mentioned in the header against which one), so it’s not a full document in itself, it’s only a ‘patch’ to a document.
This can be quite confusing, if you’re only trying to find your way around unextended OpenGL. The full core spec is quite a lengthy read
Reading the extension spec top-to-bottom is usually not the best idea at first. The template layout somewhat assumes that you already know what it’s all about. I’ve often found that after being more familiar with an extension, the layout suddenly feels right, but not so for the first read.
Fortunately, there’s an “overview” section. Start with that. This is the “what”.
Then I’d recommend looking for the new entry points added by the extension. Take one at a time, and search the document for the occurences of that name. You’ll quickly find explanations of what each function does. If there are no new functions, there should be new tokens, so search for these instead. This is the “how” of the extension.
I really found to have saved a lot of time by following this procedure. Don’t know if it works for you.
If that’s still not enough, you’ll have to read the rest of the document. If you’re doing this, save the issues section for last.