David,

if you really want to emulate the behaviour of \mathrm{\gamma} with the MC
font encoding, this is a solution to the problem.

It is not the only one, as I want to line out in some more detail:

Currently the is a _subencoding_ OMA (Old Math Alphabetic), which is a
subset of both OML (cmmi's encoding) and OT1 (cmr's encoding). It contains
the latin A-Z, a-z, the digits 0-9, and the greek special capitals \Gamma-
\Omega (including \Upsilon). This subencoding currently has something to do
with the text encoding, since cmr is both cm text roman and cm math roman
at the same time. However, the connection is not necessary.

I am thinking of a new subencoding MA (Math Alphabetic) which is in fact
OMA plus lowercase greek letters plus completed uppercase greek letters
plus some letterlike symbols (\dbar coming to my mind as an obvious
candidate for this, \partial and \Nabla, too. This list not complete.).
Then we could have a differently organised group of fonts:

     Current situation        Justin's Proposal     alternative proposal
     OT1 (cmr)                T1 (?)                MC1            *
     OML (cmmi)               MC                    MC2
     OMS (cmsy)               MSP                   MSP
     OMX (cmex)               MX                    MX             **
     U (all other)            MS1                   MS1
                              MS2                   MS2

MA is subset of both MC1 and MC2, where MC1 contains math roman and MC2
math italic. Further fonts (without symbols, but purely MA encoded) can
provide math text italic, math sans serif and math typewriter on demand.

Since It is possible to make OML (or almost all of it) a subset of MC2 and
(almost all of) OT1 a subset of MC1, compatibility to the old version can be
kept.

* T1 for math roman is not explicitly stated in Justin's proposal, as far
as I can see.

** MX may need splitting in tow parts. In this case, separating the
vertically extensible things from the horizontally extensibles ones looks
preferable to me.

--J"org Knappen