Besides the fact that this is a question which should be asked in the
Teamcenter Forum...
The revisioning scheme is configured with the BMIDE tool provided with the teamcenter installation. You can decide yourself how it should look like...
Of course there are some recommendations on how to do it. If i'm correct the o.o.t.b is going like A,B,....Z,AA,AB,AC....AZ,BA.....ZZ
In our TC environment we are starting with a - revision...
So most probably your IT department didn't allow for this revision sequence or it is not allowed to already use it before the single letter revisions are all used.
Ronald van den Broek
Senior Application Engineer
Winterthur Gas & Diesel Ltd
NX9 / TC10.1.2
Building new PLM environment from Scratch using NX11 / TC11