The OBJECT-TYPE macro is used to define a type of managed object. It should be noted that the expansion of the OBJECT-TYPE macro is something which conceptually happens during implementation and not during run-time.
For leaf objects which are not columnar objects (i.e., not contained within a conceptual table), instances of the object are identified by appending a sub-identifier of zero to the name of that object. Otherwise, the INDEX clause of the conceptual row object superior to a columnar object defines instance identification information.