Hi Fill Yan,
If you're looking by FM, please you can start reading the note and links below.
1030497 - Public sector scenarios in new general ledger;
Funds Management - Fund Accounting - SAP Library
Funds Commitment Processing Process Component - Enterprise Services WIKI - SCN Wiki
But basically the FM is used for the PSM customers. Is used another total table like a PSGLFLEXT if the customer is from Public Sector. If not, you can used FMGLFLEXT, but for both tables some fields you can't use, like a profit center, segment or business area.
JPA