scope:

This Recommendation I International Standard provides a standard notation called Abstract Syntax Notation One (ASN.l) that is used for the defímition of data types, values, and constraints on data types.

This Recommendation I International Standard

- defímes a number of simple types, with their tags, and specifies a notation for referencing these types and for specifjing values of these types;

- defímes mechanisms for constructing new types from more basic types, and specifies a notation for defíming such types and assigning them tags, and for specifjing values of these types;

- defímes character sets (by reference to other Recommendations andor International Standards) for use within ASN. 1;

- defímes a number of useful types (using ASN. i), which can be referenced by users of ASN. 1;

The ASN.l notation can be applied whenever it is necessary to defíme 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.