This is where Auto-Edit variables are defined. Auto-Edit variables are a somewhat complex topic, because there are a lot of them, and they display varied behavior.
A good place to start is the Control-M User Guide
. If you want to jump right into Auto-Edit variables, flip to p. 87, which takes you to the following section:
Part 2 - Defining the production environment > 4 Defining how jobs should run > Creating and editing jobs > Defining and using variables that are dynamically resolved at runtime