How does partial processing to an Order work on a Budget Controlled Requisition

Summary

Impact of partially processing a budget controlled Purchase Requisition into a Purchase Order

Content

I wanted to share some insight into how a budgetary controlled purchase requisition works for order processing. This was a recent customer question (and I have seen similar ones before) and thought it might be good to remind customers of behavior. 

Specific Scenario:

The purchase requisition contains a line for quantity 50 Units

This requisition is processed into a purchase order

The order is processed only for quantity 30 Units

Question:

What happens to the remaining quantity 20 Units on the purchase requisition

Expected Behavior:

When a purchase order is created from a requisition line, in the above scenario, two things happen: