Field help (PLPEXTQTY) 

Entering operation units for the period is optional et possible only on the lines of the plan corresponding to non closed periods. The number of authorized decimals depends on the chosen unit.
If the number of Planned OPE is higher than the number of Residual OPE, the total of the OPE of the production plan is revised after the validation of a confirmation message.
When the number of Planned OPE is modified, the plans depreciated according to the OU - Operation units method of the assets linked to the production plan must recalculated.