Field help (PRITYPBPC) 

This flag determines if the prices of products (sales invoices) and amounts (customer BP invoices) are expressed ex-tax or tax incl. This flag influences the price list search. Only those price lists defined in a mode or those accepting a price conversion will be taken into account.

The document price/amount type excludes or includes tax depending on the type defined at customer level.

If the supplier is connected with a customer category, this information is initialized by the amount type defined at the level of the field Price type/Amount typeof the category.