Genexus

After some research, I found that I will have to resort to using LWUs. However, according to the document I was reading, there isn’t a clear description on how I can define a LWU on a caller transaction. The examples they offered, they stated that LWUs can be defined as a single transaction, or as a procedure that is called FROM a transaction. How can I define a LWU to commit on a transaction that calls other transactions?