Thanks for all your assistance. I tried -P, -G and -x, both with and without the "-e 3", and both with the -x args you used and with the values from srid 54, but all four combos had problems:
sdelayer -o register -l zBldg2,shape -e nac3+ -t GEOMETRY -C objectid,SDE %auth -P HIGH -G102100 -x -10000000,0,10000 # created but unpreviewable
sdelayer -o register -l zBldg2,shape -e nac+ -t GEOMETRY -C objectid,SDE %auth -P HIGH -G102100 -x -10000000,0,10000 # invalid entity type error
sdelayer -o register -l zBldg2,shape -e nac3+ -t GEOMETRY -C objectid,SDE %auth -P HIGH -G102100 -x -20037700,-30241100,10000 # created but unpreviewable
sdelayer -o register -l zBldg2,shape -e nac+ -t GEOMETRY -C objectid,SDE %auth -P HIGH -G102100 -x -20037700,-30241100,10000 # invalid entity type error
So it looks like sdelayer thinks it needs the "3" entity type (even though I have no idea where it is determining that from the 2-dimensional MSSql Geometry type). Is there perhaps a way to strip the "c" and the "3" from the "sdelayer describe" attributes of the source FC (Bldg) prior to using MSSql to copy the single feature from that class to the new table Bldg2 that I'm trying to register?
Or perhaps some other way to prevent the registered layer from being corrupted?
Thanks again,
--John