cin concepts

hi,

i am new to SAP MM

can anybody tell me,why there is need of material and chapter id combination required for excise?

in TAXINN procedure excise rate is neccesary to define or not.

PLS EXPLAIN ME HOW EXCISE IS CALCULATED BY SYSTEM,WHEN RECIEVES MATERIALS.

what is the sequence of that calculation.

tHANKS IN ADVANCE

SUMIT BIS