ISO/IEC 18056:2012 specifies an XML protocol for the services defined in ISO/IEC 18051. It provides an alternative protocol to the ASN.1 based protocol specified in ISO/IEC 18052. In addition to the CSTA-specific protocol details, it also describes the concepts underlying the request/response model, application association, notation and service, and describes the template it uses. It also specifies the PICS used and provides examples of CSTA XML encodings.