Item Data Relevant to All Items 
The following section describes the fields in which you make entries for all the items in a BOM. It also describes the item data determined by the system.
- Item number
This number is used to sort an item within the BOM. You can sort the items in ascending order of item numbers.
In Customizing for Production, you can define a value by which the item number is increased (for example, 0010, 0020, 0030, and so on) by choosing Bill of material → Define user-specific settings.
- Component
To identify the objects you are entering as components of a BOM, you enter certain data from the object master record. For more detailed information, see the specific topics on material items, document items, and class items.
- Component description
If the component has a master record (for example, a material master record), this description is taken from the master record.
- Component quantity
In this field, you enter the quantity of the component required to make the base quantity of the product. You must enter a component quantity.
- Unit of measure
This field shows the unit of measure for the component quantity. For more detailed information, see the specific topics on material items, document items, and class items.
In Customizing for Production, you define a unit of measure for piece in the Unit of measure ‘piece’ field by choosing Bill of material → Control data for bills of material → Define modification parameters. This unit is the base unit of measure for the following item categories:
- Text item
- Document item
- Non-stock item without a material master
- Item category
When you create each new BOM item, you must assign the item to an item category. This field is defined as a required field on all screens for entering items. The item category defines data entry and processing for an item.
- Item IDs
A BOM item is uniquely identified by its item ID.
The system makes the following checks:
- Change number , Valid from date, Valid to date
The system sets this validity data automatically. This data shows the validity period of the item within this BOM.
- Assembly
If the component has its own BOM, the system sets this indicator.
- Sub-Items
If the item has sub-items, the system sets this indicator.