M=Member ID and S=Subscription ID

Please note the two ID numbers listed on the order page. The S-number is
the subscription ID, and the M-number is the member ID.

From within an individual order, admin can drill down to either the CSA Member data screen or the CSA Subscription screen.

Remember each member has a unique member Id, but one member can have
multiple subscription Ids. (Multiple shares or shares over several seasons
are two examples.)