Scheduling agreement target quantity

[Fakeittillyoumakeit]

Hi, 

Regarding the scheduling agreement(ME31L, ME32L, ME33L), there is a target quantity. 

I was under the impression that the orders could not be placed after reaching the target quantity, but I've heard that orders can still be processed beyond this limit. In this case, I'd like to understand why the target quantity needs to be entered.  What is the function of the target quantity? 

Thank you for your consideration.