Using "Customer Fields" tab in Maintain Service Processes

In the Change Request transaction under Transaction Data there is a Tab for "Customer Fields".

Can anyone tell me how to use this tab.

- Is it a BAdI (If so can you tell me which one).

- Is it an enhancement (If so which one).

- Is it something new?

I checked the program and found the only related BAdI for this package was CRM_ACTIVITY_APPEND. I tried activating it to no avail.

Any suggestions on how to proceed are appreciated.