In Customizing for Engineering Change Management, under Set up control data, you can define a time frame for additional date checks in the Date shift dataset. You define a protected time period that is checked in the following processing situations:

• Change master record maintenance

• Entering the valid-from date
• Entering an alternative date
• Shifting the valid-from date or an alternative date
• Allocating an alternative date to a change object or deleting the allocation

• Processing a change object with reference to a change number with a valid-from date in the protected time period

• Changing a change object (for example, BOM or task list)
• Assigning or changing a revision level

For this date check, you can specify whether a warning message or an error message is displayed when you try to perform these functions within the protected time period.

For example, you can specify that changes in the past are not allowed. Process flows for Materials Requirements Planning (MRP) may be relevant to the change. If materials have to be replaced by new materials, the replenishment lead time must be taken into account when you change the BOM.

The baseline date for the check is the current date. The system calculates the warning or error time (in calendar days) either forwards or backwrds in time from the current date. The protected time period covers the key date calculated and all dates before this date.

• Warning time in days

• Error time in days

Suppose you want to perform a date shift on the valid-from date of a change master record. The following settings are defined in Customizing:

If you attempt to shift the valid-from date of your change master record to October 15, 1997, a warning message appears because October 15, 1997 is in the protected time period. If you confirm the warning message, you can shift the date to October 15, 1997.