There are, IIRC MNP-0 thru MNP-7 or some similar range. MNP-2,3, and 4 are part of V.42. If one of those is what you need maybe you can get your hands on the V.42 spec. Which of the MNP levels do you need?
--traveler
Comment on Re: Implementing MNP (Microcom Networking Protocol) in Perl
Though I didn't know at the time of posting, I need MNP-5. Apparently my friend needs to take advantage of the compression features of that class of MNP.