How to understand the "External System" field found on a Job's Additional tab in Confirm

On the Additional tab of the Job screen in Confirm®, External System fields, that is Name, Order Reference and Job Reference, are optional. These are populated by data coming in from the Contractor Access Agent.

Note: These fields are only displayed if Module 1620 (Contractor Access Agent) is enabled.
UPDATED:  October 6, 2017