How does this variable ~Parent(1)~ work when shredding Copybooks?

Products

• CA Test Data Manager (Data Finder / Grid Tools)

Issue/Introduction

We are trying to modify and improve the speed of the scripts that are generated.  

The customer had removed this in a few spots and put in some others (I think a direct pointer to a column in another derived/shredded table.) 
As we did this, we figured out it was affecting the publish action to FDM in the portal.
How does the variable know what the parent is for say ~(Parent(!)~?

Environment

TDM 4.x
Web Portal
Test Data Manager

Resolution

The ~PARENT(1)~ variable is used alongside the foreign key relationship.
So the portal knows to which parent column it should refer to by checking the FK relationship and then picking up the corresponding row, in this case row 1.