Commitment Control in Inventory Transfer through Interunit MSR

Can someone explain me the Commitment Control transactions in Inter Unit MSR in Inventory?

I understood through PeopleBooks that if you process a MSR, system records Expense against the Budget Chartfields entered in the MSR. But no where i found the detailed explanation about how it would behave in different kind of MSRs ( InterUnit MSR, External MSR, Internal MSR and MSR Return).

Thanks,

Satish