Prefixes in lua source code lua_, luai_, etc.

[John W <jwdevel@...>]

I feel like I read some explanation for this, but can't find it any more.
What are the meanings of the various prefixes seen in the Lua source code?

eg: lua_, luai_, l_

Are these documented somewhere?
I just want to make sure my patches to be copacetic with the naming conventions.

Thanks
-John