It specifies the requirements for fieldbus component parts. It also specifies the media and network configuration requirements necessary to ensure agreed levels of data integrity before data-link Layer error checking and interoperability between devices at the physical layer. The fieldbus physical layer conforms to layer 1 of the OSI 7-layer model as defined by ISO 7498 with the exception that, for some types, frame delimiters are in the physical layer while for other types they are in the data-link Layer. It includes the following significant technical changes with respect to the previous edition deletion of the former Type 6 fieldbus for lack of market relevance; addition of new fieldbus types; generalization of the seldom-used Type 1 radio to a more useful form.