TNM MIB Data Types
Every MIB object has an associated data type. The set of primitive data types is defined in the SNMP SMI (see the snmp man page for a list of supported SNMP SMI data types).
Derived types are either explicitly defined by the invocation of a TEXTUAL-CONVENTION macro or implicitly by putting value restrictions or enumerations in an OBJECT-TYPE macro.
ASN.1 type assignments are also used to created derived types. The Tnm extension converts implicit type definitions and ASN.1 type assignments into explicit type definitions in order to handle both in a uniform way.
A data type is referenced by the type name.
A type name is constructed out of the module name which contains the type definition, an exclamation mark and the type label.
A type label for an explicitly derived type is the label used in the type assignement. The label for an implicit type is the capitalized label of the OBJECT-TYPE macro which was used to define the type.
For example, the string SNMPv2-TC!DisplayString
refers to the DisplayString textual convention defined in the SNMPv2-TC
module. The string IF-MIB!IfOperStatus refers to the implicit type definition
in the IF-MIB module for the MIB object ifOperStatus.