If you perform a date shift that changes the sequence of effectivity periods of a BOM, two effectivity periods may overlap. This means that different item versions with different change numbers exist in the overlap period.
Example: Effect of Date Shift on a BOM Item
Suppose a BOM item is created at time t1.
For each item change made with reference to a change number (N1, N2, and N3), the system creates an item record for the effectivity period concerned (A, B, C, and D).
Graphic: Date Change with Overlapping Period
The graphic below illustrates how an overlap period can come into existence.
The first section shows the time period in which the item was created and then changed with three change numbers. Then a date shift is performed on change number N2 (the valid-from date is shifted into the past).
The second section shows the result of this date shift.
This has the following effects:
You can perform this date shift if only the sequence of effectivity periods for bills of material changes as a result, and if the system is configured such that a warning is displayed. To proceed with the function, you must confirm the following message:
Date shift changes sequence
Since the sequence of effectivity periods changes, a temporary log for bills of material is produced.
Controlling the BOM Explosion in the Overlap Period
If you process the BOM in the overlap period, versions of the item exist with different change numbers.
You can define which item is valid for the BOM explosion in Customizing for Bills of material, underDefine modification parameters. With the indicator Explosion BOMitm. (Explosion control for BOM items) you control whether and according to which rules the system determines a unique change status. This occurs when you display, change, or assign values to a BOM for a date within the overlap period.
You have the following options:
The system determines all item versions. They are listed with the same item number and the different change numbers.
Example from the graphic Date shift with overlap period:
If you process the BOM in the overlap period, any item that was changed with change number N2 is listed twice. In this case, you should process the item with the change number that has the more current valid-from date (change number N2, in this example).
If more than one item is valid in an overlap period the system determines the one that was created last.
If more than one item is valid in an overlap period the system determines the one that was closest to the current date.