Field help (AWATYPWRK) 

It defines whether a Workflow is going to be triggered on each detail line or only on the header.

This field is not entered, it is only displayed :

If no allocation rule has been given, but there is an associated model integrating links (1,N), the field is entered. Then it is possible to choose whether the Workflow will be triggered at line or header level (remembering the fact that the lines can be regrouped to send a notification by group).