formation. Any resource that has to be managed is referred to as managed object and is rep- resented by a class called the managed object class. Defining generic guidelines for information representations helps to create specific subclasses from the generic parent classes in SMI. The main ITU-T documents on SMI are: X.720 Management information model: It defines the concept of managed object and managed object class. The principles for naming managed objects, the attributes in managed objects, and the relationships like inheritance, Information Handling Test INTEGER :: = 0 Identifier Length Contents 00000000 Value 0 (two's complement) Universal Integer (2) Primitive (0) 00000001 Length = = 1 Figure 15.3 Example of BER encoding. specialization, and containment associated with managed objects are also discussed in this document. X.721 Definition of management information: It defines the managed object classes that are required for systems management functions. X.722 Guidelines for the definition of managed objects (GDMO): It speci- fies the syntax and semantics for the templates in SMI-like managed objects, attributes, notifications, actions, and SO on. X.723 Generic management information: It defines the managed object classes at different layers or more specifically at resource level like ports. X.724 Requirements and guidelines for implementation conformance state- ment proformas associated with OSI management: It relates to conformance testing of managed objects and systems management functions. The management information is stored in a management information base (MIB). The data can take two forms. It can be a "Scalar" like integer, character, and SO forth or it can be a "Table" that is a two-dimensional array of scalars. While scalar can be used to store the value of a variable in the managed object, the table can be used to capture different instances of the managed object. As already mentioned, SMI is defined using ASN.1 constructs. The data types for SMI can be classified into three groups. They are: Simpl