M2 is M1 plus time related deposits.
M3 is the total estimated (WAG) amount of a currency in existence in any form.
The CB can interject extra money into the system at each of the 3 levels although the national Treasury and Mint usually have oversight and control of M1. Whether a CB uses M2 or M3 depends on the policies (goals) and the situational analysis and decision making processes of the various CBs.
(And you thought I couldn't drag in Epistemology, huh? :-)
