(Guidelines for Definition of Managed Objects) The rules for defining the elements (objects) that are managed in a LAN (workstations, servers, switches, etc.). Supported by the CMIP and TMN management standards, the resulting descriptions are used in MIBs for network management. GDMO provides a strict inheritance hierarchy for object classes and a tree structure for object names. ASN.1 is used for syntax. See CMIP, TMN, MIB and ASN.1.