Urgent: ABAP routine in transfer rules

Hi,

when i am loading master data from R/3 into BW, i need to filter some records based on material type. there is no option in RSA6 (on R/3) or in Infopackage (BW) to make it available for filter.

So i assume i need to write ABAP routine in transfer rules. can some one help me with ABAP. i need to load the records only when MTART field(material type) in MARA is "FINI" or "RAW" and skip other records.

what is difference between deleting the whole data packet and deleting the record.

Thank you very much in advance

Regards

Emil