Sure, whatever, @m would work too. @mouse would bring it closer inline with focus/target/cursor in terms of length. Anything less than 8 characters would be an improvement.
Yeah, I’m pretty sure I’ve seen a few characters named “Mouse” 
It’d have to be a one-character tag (and @m sounds wonderful to me), include a special character not usable in names, or there’d have to be a purge/block of names of whatever the abbreviation turns out to be.
Would love for Totems to have a cancel mechanism like Temp. Enchants.
With Totems moving to being created from a pool in Dragonflight, having to use the default TotemFrame because, for some unknown reason it’s the only way to cancel totems, becomes even more of a PITA.