This top level document describes the network in general@ the OSI layering structure@ the subordinate document structure@ and provides control for all preassigned values and names. The Appendices of this document lists all SPN assignments@ PGN assignments@ NAME Function assignments@ Manufacturer Code assignments@ and Preferred Address assignments. All SPN and PGN assignments are listed in this document even though the complete definition details might be recorded in another standard. The SPN and PGN listings in this document identify the standard document that either contains the definition details or is associated with the identifier. Degree of Openness An SAE J1939 network is open to the degree that any two ECUs which conform to the same SAE J1939-0X document can be connected via the network and communicate with each other without functional interference. The SAE J1939-0X documents describe a specific type of application@ typically representing a specific industry to which it pertains such as agricultural or heavy duty trucks. ECUs which conform to a different SAE J1939-0X document may not be capable of communicating directly with one another and in some cases may cause degradation or complete disruption of the entire network. Proof of Compliance There is no procedure presently in place to test@ validate@ or provide formal approval for ECUs utilizing the SAE J1939 network. Each developer is expected to design their products to the spirit of@ as well as the specific content of@ this recommended practice. Provisions are made in SAE J1939-11 and SAE J1939-15 for self certification to these documents. In the future@ additional procedures may be defined and implemented to test new products to ensure full compliance with all appropriate SAE J1939 documents. Until that time@ compliance will be determined by the manufacturer of the component. Should questions arise regarding the use or interpretation of any part of these recommended practices they should be directed to the SAE Control and Communications Committee for resolution.