UltraXML Solutions for Automotive & Trucking Industries

SAE J2008

SAE J2008 is a family of standards developed by the membership of the Society of Automotive Engineers in response to the mandate of the Clean Air Act to partition and provide easy access to emission-related automotive service information. At the heart of this standard is a relational Data Model for Automotive Service Information rather than any particular SGML document model. The SGML definition set forth within J2008 provides a hierarchical representation of the Data Model. In addition, this standard provides models for common text constructs such as tables, paragraphs, lists, and procedures which are found within automotive service information.

Today, the J2008 is adopted by many car manufacturers around the world.

J2008 Work Groups

Work groups were formed to focus on specific technical areas. Work groups operate on a consensus basis and present the results of their efforts to the J2008 task force. The J2008 task force approves the efforts of the work groups and resolves issues that cannot be resolved in work groups. The task force operates on a majority vote basis. The following technical work groups were formed:

• Data Modeling
• Graphics Standards
• Document Type Definition
• Data Interchange

Data Modeling Work Group

The Data Modeling work group created a logical data model for service information. Simply stated, a logical data model described the relationships between real things. The data model identifies all of the things, or entities, required to organize service information. Users can locate service information that is linked to a particular entity by identifying which of these entities they are dealing with on a vehicle. For example, many vehicles have an engine, and accepted methods exist for identifying both a vehicle and an engine. If users know that they need service information about the engine, they can access that information by requesting information about the engine.

An engine is a simple example, since it is a clearly defined part of a vehicle. Most people can agree what components make up an engine and can identify what engine they are dealing with. A fuel system is also a real thing, but it is much more difficult to define than an engine. Not everyone agrees exactly what components make up a fuel system. Fuel systems vary greatly among models and are constantly changing. The data model is designed to organize and provide users with access to information about both simple entities (e.g., engine) and complex entities (e.g., fuel system).

Two key data modeling objectives were to achieve a degree of standardization in service information and to provide flexibility in the access of the information. Both of these objectives were accomplished through the development of a logical relational data model. All J2008 information provided by OEMs will adhere to the standard organization outlines by the data model. Given that service information exists on a particular topic, it must be stored and exchanged in accordance with the standard. Each aftermarket intermediary can use any of the standard relationships in the design of their delivery platform that they perceive to be of value to the end users.

The logical data model is relational in the sense that the terminology used to describe and document it is relational. Implementation of the logical data model by OEMs or the aftermarket intermediary can take many different forms. A relational data base is one form of implementing the data model. There are object-oriented, hierarchical or keyed flat file data bases which all perform similar functions. Thousands of relationships are documented in the data model, but only a limited number will be delivered to the end user.

Graphics Standards Work Group

The graphics standards allow the use of either raster or vector formats. Today, most graphics for service information are in raster format. Of those raster graphics, over 90% are black-and white (monochrome or bi-level) images, but grayscale images are becoming more prevalent.

Raster Graphics

The specific standard selected for graphics is the Tagged Image File Format (TIFF) 5.0 Class X with additional tag support and without LZW compression. The selected standard allows four image types (Monochrome, Grayscale, RGB Color and Palette Color) and five industry standard compression schemes.

Vector Graphics

The selected standard for vector graphics is the Computer Graphics Metafile (CGM) defined by Air Trans-port Association (ATA) Specification 2100 Digital Data Standards for Aircraft Support (Data Interchange 3.3.2 Graphics Exchange GREXV24

Document Type Definition DTD) Work Group

The J2008 Task Force has used SGML to create an automotive industry standard for exchanging service information.

Document Analysis is a necessary step in the development of any SGML application. During analysis, the J2008 task force studied service related documents from multiple OEMs which were analyzed for structure and content. Each content element of the documents, along with the relationships between those elements of the documents were embodied in the J2008 DTD. The implementation of a DTD ensures consistency in the information's structure. A tag set is provided as a result of defining the elements of that structure.

J2008 information is associated with a manufacturer, and to a vehicle when possible. Service information may be further divided into the Service Categories (logical divisions of service information), Configuration Groups (physical divisions of a vehicle or component), and Component related information. Each of the selected major divisions of service information must further be divided into service information types. A set of tagged service information is known as a document instance. The DTD allows the sender and receiver of SGML tagged information to automatically verify the integrity and structure of the data exchange; thereby ensuring accurate economical and speedy delivery of service information.

An XML DTD for SAE J2008 was created by converting the SGML DTD.