which function module called CIF material transfer

Hi ,

I am trying to transfer material data from SAP ECC to SAP APO through CFM1.

How to find which function modules are called using data  transfer > I need to put external breakpoint in SAP APO end so that during transfer I come to know that particular function module is called

IS there any standard function module which is called for all CIF data transfer  or if not please help me which FM is called for Material transfer .

please explain me the steps .