This document discusses restricting the update of a sub-inventory field for sales order lines when an internal requisition is created. It provides the steps to set up a form personalization that makes the sub-inventory field non-updatable for sales orders linked to internal requisitions. The process involves opening the sales order screen, adding a personalization to restrict the sub-inventory update, defining a condition to check for an associated internal requisition, and configuring an action to make the sub-inventory field read-only. This form personalization prevents changes to the sub-inventory after order creation when an internal requisition was the source.