There are lots of different ribs. The one you mentioned is one of them. There is a K2, P2 rib. There is a twisted rib, etc. Unless the pattern specifies exactly what rib to use, I would assume the choice is yours.

Certainly on English Patterns if it says rib ** it usually means 1 plain 1 purl

Kate, did you figure it out? I would assume that somewhere in the beginning they would establish the rib pattern (like tell you to k1, p1 or k2 p2 or something like that) and from there on you would rib in the same pattern. If they don't tell you, you may be able to tell by looking at the picture, and if that doesn't work, I guess you can just do whatever pleases you!

Donna