SAE J2534-1 defines a standard vehicle network interface that can be used to reprogram emission-related control modules. However, there is a need to support vehicles prior to the 2004 model year, as well as non-emission related control modules. The SAE J2534-2 document meets these needs by detailing extensions to an SAE J2534-1 specification. It is not required for an interface to be fully compliant with SAE J2534-1 specification to implement some of the features specified in this document. Together, these extensions provide the framework for a common interface to protect the software investment of the Vehicle OEMs and Scan Tool manufacturers. Only the optional features will be described by this document and are based on the December 2004 publication of SAE J2534-1.