You may want to specify what SAP is doing exactly and what you want to know.

Scenerio : 

BOM code is a dummy code for bill of materials. 

Bill of materials under the BOM code will have base price and asp. 

BOM code can be set with price where bill of materials can be updated

BOM : 900008         - Rs. 1,00,000

Material 1: 100001 -  Rs. 90000

Material 2: 100002-Rs. 5000

Material 3 : 100003 -Rs. 5000

Above is the BOM price and if user want to change the material 2 to 0 value and include the amount to BOM, system should allow. 

Above prices are only for BOM level and base price and ASP remain same.