Any UDF that shows in the CustomerCenter is Required to follow the rules set on the UDF by the Administrator. If there are User Defined Fields (UDFs) associated with the Service Catalog, Service Desk Actions, or Service Orders that have the "Show in Cust Center" flag set to true, they are displayed on the Request.
Action UDFs, Service UDFs, Service Order UDFs, and Incident UDFs are the four types of UDFs that appear in CustomerCenter, but only Action UDFs, Service UDFs, Service Order UDFs will show up in the Cart. At this time, Equipment UDFs will only show up on “Incident Request”, not Service Requests or Service Actions. Service UDF's show up in a section above "Additional Information" with a heading of "Information for <service ID>" i.e. "Information for Fantastic Company”.
For more information on UDFs in the CustomerCenter please see the CustomerCenter section on the User-Defined Fields page.