Having thought about this now for more than 5 minutes (I know, my attention span is truly awesome, isn't it?

) I voted "other".
Tech, if we really have to have a standardized abbreviation, I suggest '
BSh' (or 'BSH', 'bsh' - for the
one-finger typists) because,
(a) it seems the most unambiguously understandable, and
(b) it alludes to the avast! 4.x file shield name 'ash' with which some of us are already familiar.
If Behavior Shield was '
BSh'
File Shield could be '
FSh'
Mail Shield '
MSh'
Web Shield '
WSh'
P2P Shield '
PSh'
IM Shield '
ISh'
Network Shield '
NSh'
Script Shield '
SSh'
Virtualization (Shield) '
VSh'