ABSTRACT
This chapter reviews the most common, early data exchange methods and standards. The need to transfer data between engineering applications has existed since before the development of the first computer-aided design (CAD) systems. In the middle 1970s, CAD system companies learned of the need for data exchange from their customers, and some developed means for reading data into and writing the data out of a CAD project file. The neutral file is a response to the combinatorial problem that arises when several engineering applications need to exchange data. The chapter also reviews the four examples–the arc, the planar surface, the solid and the wall. In the late 1980s, they responded to the demands for data exchange by defining a public, external file format called Data Interchange Format. The file format consists of five sections: a header section, a tables section, a blocks section, an entity section, an extended entity section and an object section, followed by an end-of-file marker.
