In computing, an object identifier or OID is an identifier used to name an object (compare URN). Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the ITU-T's ASN.1 standard. Successive numbers of the nodes, starting at the root of the tree, identify each node in the tree. Designers set up new nodes by registering them under the node's registration authority. The root of the tree contains the following three "arcs":

• 0: ITU-T
• 1: ISO
• 2: joint-iso-itu-t

Usage

• In computer security, OIDs serve to name almost every object type in X.509 certificates, such as components of Distinguished names, CPSs, etc.
• Within LDAP schemas, each attribute type has a unique OID
• In computer networking, an OID, in the context of the Simple Network Management Protocol (SNMP), consists of the object identifier for an object in a Management Information Base (MIB).
• In computer programming, an object identifier generally takes the form of an implementation-specific integer or pointer that uniquely identifies an object.

Examples

The most common OIDs seen "in the wild" usually belong to the private enterprise numbers allocated by IANA under the 1.3.6.1.4.1 (iso.org.dod.internet.private.enterprise) arc.

External links

• Object Identifier Tree
• Harald Tveit Alvestrand's Object Identifier Registry
• IANA Private Enterprise Numbers

Identifiers