Provides a standard notation called Abstract Syntax Notation One (ASN.1) that is used for the defintion of data types, values, and constraints on data types. This Recommendation / International Standard defines a number of simple types, with their tags, and specifies a notation for referencing these types and for specifying values of these types; defines mechanisms for constructing new types from more basic types, and specifies a notation for defining such types and assigning them tags, and for specifying values of these types; defines character sets (by reference to other Recommendations and/or International Standards) for use within ASN.1; defines a number of useful types (using ASN.1), which can be referenced by users of ASN.1; The ASN.1 notation can be applied whenever it is necessary to define the abstract syntax of information. It is particularly, but not exclusively, applicable to application protocols. The ASN.1 notation is referenced by other standards which define encoding rules for the ASN.1 types.