Duff-Man says....."RevA" refers to the first issue of a particular model/style - for instance the very first release of the 12" Powerbook at MacWorld 2003 (the 867mhz Aluminum) was a "Rev A." When Apple refreshes the line with faster processors etc but does not change the form-factor (or style of the computer) it is then refered to as "RevB" then "RevC" etc etc...you get the idea....oh yeah!