The primary purpose of characteristics on customer contacts is to allow a letter to extract information from any object in the system; such as, a field activity, or case. For example, if an algorithm or background process generates a letter related to a Case, you could create a customer contact and reference the case as a characteristic value. When the letter’s information is extracted, the extract algorithm can extract the fields from the case to merge onto the letter. Refer to Customer Contacts Are Used To Trigger Letters for more information

You can only choose characteristic types defined as permissible on a customer contact. Refer to Setting Up Characteristic Types & Their Values for more information about characteristic types. In addition, the characteristic type must also be defined as valid for the customer contact's type. Refer to Setting Up Customer Contact Types for more information about customer contact type.