I've heard that terminology used by Jerry Coker in his Hearin' the Changes book. His M.W. bridge is the one that goes to the IV and S.R. is the typical dominant chord cycle of I Got Rhythm. He uses those terms to indicate how common those two variations are. Of course, both MW and SR are disappearing from popular culture, so the reference is probably lost on younger people.
I use that book for my jazz ear training class, I like it a lot.