Scope and field of application This Recommendation specifies a notation for abstract syntax definition called VAbstract Syntax Notation One (ASN.1). This Recommendation defines a number of simple types@ with their tags@ and specifies a notation for referencing these types and for specifying values of these types. This Recommendation defines mechanisms for constructing new types from more basic types@ and specifies a notation for defining such structured types and assigning them tags@ and for specifying values of these types. This Recommendation defines character sets for use within ASN.1. This Recommendation 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 also referenced by other presentation layer standards and Recommendations which define encoding rules for the simple types@ the structured types@ the character string types and the useful types defined in ASN.1.