BOM Changes in the SAP R/3 System 
In the R/3 System, you can change bills of material either with or without saving a history.
- Change without history
A change made during the development phase of a product that does not need to be document.
The state of the bill of material before the change is not stored. You can only process the data you last saved.
- Change with history
A change that may require further activities within the company and which must be verified (for example, Change BOM → Change routing → Change inspection plan).
Engineering change management in the R/3 System enables you to document all changes.
- The header and item records are duplicated.
- Changes to sub-items are not saved historically, even if you make these changes with reference to a change number.