SAE J1939文件适用于道路上或非道路上使用的轻型、中型和重型车辆，以及使用车辆衍生部件（如发电机组）的适当静止应用。感兴趣的车辆包括但不限于公路上和非公路卡车及其拖车、施工设备、农业设备和机具。这些文件的目的是为电子系统提供开放互联系统。这些文件的目的是允许电子控制单元通过提供标准体系结构相互通信。本特定文件SAE J1939-21描述了使用经典扩展帧格式（CEFF）的数据链路层，29- 比特ID，如2015年12月ISO 11898-1中所定义。对于SAE J1939，不允许使用其他数据链路层。

The SAE J1939 documents are intended for light, medium, and heavy-duty vehicles used on or off road, as well as appropriate stationary applications which use vehicle derived components (e.g., generator sets). Vehicles of interest include, but are not limited to, on- and off-highway trucks and their trailers, construction equipment, and agricultural equipment and implements.The purpose of these documents is to provide an open interconnect system for electronic systems. It is the intention of these documents to allow Electronic Control Units to communicate with each other by providing a standard architecture.This particular document, SAE J1939-21, describes the data link layer using the Classical Extended Frame Format (CEFF) with 29-bit IDs, as defined in ISO 11898-1, December 2015. For SAE J1939, no alternative data link layers are permitted.