This Recommendation / International Standard specifies a set of basic encoding rules that may be used to derive the specification of a transfer syntax for values of types defined using the notation specified in ITU-T Rec. X.680 (1994) / ISO/IEC 8824-1:1995, ITU-T Rec. X.681 (1994) / ISO/IEC 8824- 2:1995, ITU-T Rec. X.682 (1994) / ISO/IEC 8824-3:1995, and ITU-T Rec. X.683 (1994) / ISO/IEC 8824-4:1995, collectively referred to as Abstract Syntax Notation One or ASN.1. These basic encoding rules are also to be applied for decoding such a transfer syntax in order to identify the data values being transferred. It also specifies a set of canonical and distinguished encoding rules that restrict the encoding of values to just one of the alternatives provided by the basic encoding rules.
These encoding rules are used at the time of communication (by the presentation service provider when required by a presentation context).