Visual Integrator imports to WO.Master... perform logic details?

SOLVED

v2018.2 (Standard).

VI job to create WO from csv (set up by someone else, prior to upgrading to v2018).  The current problem we are dealing with is that the Req for WO value in IM_ItemWarehouse is not being populated properly (for component items) and I suspect it may be caused by imported WO missing something.

Sage KB 50695 indicates that Perform Logic is required... but with no details of what that perform logic should be.  Just this cryptic implication that there are two steps required.

"Note: There may be one Detail Record with both a Before Write perform logic and an After Write perform logic, or there may be two Detail Records, one with a Before Write perform logic and the other with an After Write perform logic."

Where can I find details of how to configure the PL properly?  I only see the After Write step in my job, and have no clue how to add the second PL.

Edit: fixed a typo.