What is "private enterprise number"

n. A unique number as assigned by IANA to identify unique objects that are defined by an enterprise, developed to give objects a common naming system via the more common language of numbers.

Private Enterprise Numbers (PENs) are created and maintained by the Internet Assigned Number Authority in a public registry, including a publicly revealed email address and "contact name". Any private enterprise (organization) may request, at no cost, a Private Enterprise Number (PEN) to be assigned. All applications are reviewed manually, and the requirements are not explicitly documented. Although the list of PENs includes contact names like "Engineering MIB Administrator", IANA may reject applications if the contact name doesn't 'look like' it corresponds to a real person.

Enterprise numbers are commonly used in the Management information base (MIB) files of the Simple Network Management Protocol (SNMP) and in vendor suboptions of the Dynamic Host Configuration Protocol (DHCP).