RFC: CDDB Protocol extension suggestion -- use the MCN?

A number of times I've run into this situation where a CDDB look up
returns a title that really has nothing to do with my CD. 

CD-DA's do have a media catalog number or MCN, and although very few
applications use this (currently) or know how to get it, it could be
used to disambiguate CDs and allow for more CD titles which would
otherwise conflict. 

Comments about extending the protocol to allow for an optional MCN to
be given to disambiguate? 

Thanks.