Even when a patron attribute is marked as "Unique identifier," the SIP2 server cannot find patrons using that attribute value. SIP2 lookup is hard-coded to cardnumber/userid and does not consider extended attributes, even when it is unique. Actual Result: SIP2 returns "|AFInvalid cardnumber" when the SIP client sends a value stored in a unique patron attribute. Expected Result: SIP2 should be able to search by any patron attribute marked as a unique identifier. Impact: - Self-check machines using HID/NFC values fail - Access control systems relying on alternate IDs cannot authenticate patrons I plan to submit a patch that will allow unique extended patron attributes to be used in SIP2 requests.