IEC 61158-3-20 Ed. 1.0 b:2014

IEC 61158-3-20:2014 defines the services provided to the Type 20 fieldbus application layer at the boundary between the application and data-link layers of the fieldbus reference model and systems management at the boundary between the data-link layer and systems management of the fieldbus reference model. Type 20 DL-service provides both a connected and a connectionless subset of those services specified in ISO/IEC 8886.