Before You Create a Simple Material BOM 
When you first create a BOM for a material, it is a simple material BOM. You can extend the BOM at any time to make it a variant BOM or a multiple BOM.
To ensure that you can enter all the data you require for the BOM quickly and easily, you should establish the following points before you start:
- Does a material master record exist for the material for which you want to create a BOM?
- Which usage do you want for your BOM?
Do you usually process BOMs with one specific usage? If so, you can define a default value.
- Can you use the material type of the header material with the usage you require?
- What area of validity do you want for your BOM?
- What validity period do you want for your BOM?
- Do you want to create a BOM that is subject to engineering change management? If so, which change number do you want to use?
- Do you want to assign a name to the BOM group? Which convention do you want to use?