Which item class to select in excise regime for item classification R12.1.3

HI,

In the setup -item setup> vat/excise item classification,  the item class under Excise regime available are:

CCEX, CCIN, CGIN, FGIN, FGEX, RMIN, RMEX, OTEX, OTIN.

For items which are spares like mechanical parts or electrical parts which are part of the factory / machinery and excise is applicable. For such items what is item class to be selected from the above..

Similarly for packaging material used in factory, for such items, as excise is applicable, what is item class to be select from the above.

Please advise.

Thanks

mythson