Found another Mac mouse - test-drb@ccmp.vtda.org

27 Nov 2002

...
 The leading A2 certainly means it's an Apple
product relating to the
Apple II family, but the M doesn't make it a mouse.  Lots of things
were A2Mxxxx, and only a tiny number were mice. 
Sorry, brain fart on my part. You are of course correct. A good number of 
items have M in the model number that are not mice (for instance, the 
entire(?) Mac line).

-chris
<http://www.mythtech.net>