It's the Revised Revised Revised Revised Revised Revised Revised Report on the Algorithmic Language Scheme, or (Revised)^7 Report on the Algorithmic Language Scheme, or R7RS.

(Because, of course, Scheme folks couldn't resist the urge to use a little recursion in the name of the spec instead of defining it as an iterated series of version numbers.)

But its both. Even if you don’t get the joke, you can pretty easily tell that R4RS, R5RS, RNRS represent an ordered list.