ISO/IEC 21823-4:2022 specifies the IoT interoperability from a syntactic point of view. In ISO/IEC 21823-1: Framework [2], five facets are described for IoT interoperability, i.e. transport, semantic, syntactic, behavioural and policy. In this document, the following specifications for IoT interoperability from syntactic viewpoint are included; – A principle of how to achieve syntactic interoperability among IoT systems which include IoT devices – Requirements on information related to IoT devices for syntactic interoperability – A framework for processes on developing information exchange rules related to IoT devices from the syntactic viewpoint