Excise invoice

Dear all,

I am very much new to MM CIN. When a raw material start from vendor place it carries excise invoice. This is captured at our gate. What happens next? When we send RFQ to vendors, did we mention excise conditions in it? if yes. how?AT prsent we have just added a simple pricing procedure like gross-price-discount=net price for purchasing documents.So where does excise related condition are given?

In which purchasing document or step, excise details are required like pr , po ,migo etc.?

Pls. help

Regards,