Im trying to use the optional variable pass on but im having a bit of confusion where to find the variables.

Directions

This feature allows you to pass additional information to your commission records. In addition to the (default) order number, you can pass other items such as the customer name, IP address, street address, item(s) purchased, etc. You can pass up to 3 additional items.

Integration Profile: Zen Cart
For information about which variables are available, consult your shopping cart provider.
When entering the variable name, enter it exactly as it was given to you by your provider


Any help would be greatly appreciated.