Private Enterprise Numbers (PENs) are a technical protocol parameter frequently assigned for use in the management of network connected equipment or software via SNMP-based network management systems, LDAP, DIAMETER or GSS-API. This document discusses what a Private Enterprise Number (PEN) is, common uses of PENs, and registration procedures for IANA Considerations. The registration procedures include instructions and requirements for obtaining a new Private Enterprise Number, modifying existing numbers, and the removal of existing numbers.