ISO/IEC 8824-1:2008 specifies a standard notation called Abstract Syntax Notation One (ASN.1) that is used for the definition of data types, values, and constraints on data types. ISO/IEC 8824-1:2008 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 ITU-T Recommendations and International Standards) for use within ASN.1