In Item Master Data > Planning Data tab you can define Tolerance days.
Related to order scheduling: If there is negative stock in the time line, the item will be shown in MRP as shortage. Here you can enter the number of days. A negative balance will be tolerated.
Stock = 0
Sales order = 3rd May
Purchase order delivery date = 6th May
Material comes 3 days late
If tolerance date for this item is defined with 3 days or more, the result is: OK
If tolerance date is < 2, the MRP must inform you.
In MRP the filter "Only shortage" means:
Display all entries which have a negative balance in the timeline.
(MRP Filter - Predefined Filter)
In this example the item has a balance from 0, but a negative balance between 3 and 6 May
MRP displays this item if the item has "tolerance days" < 3 days.
MRP does not display this item if the item has a "tolerance days" > 3 days.
Negative Balance in past
Negative Balance in past will be ignored entirely.
The calculation for the time area starts from the current Date.
Today is 5th May
Sales Order is 3rd May
Delivery = 6th May
The system calculates: Balance is negative from 5th – 6th May = 1 day.