Product Definition Data Interface (PDDI)
IGES provided a very practical first solution for CAD data exchange, complete with an exchange file format. It was remarkable in the speed with which it was developed, due in part to the relatively limited scope, the small size of the committee working on it, and a commitment to produce a draft within three months. Once it fell under the scrutiny of an ever-broadening community, weaknesses were identified that eventually justified embarking on a new standard that could break tradition with IGES. The Air Force ICAM program again made a significant contribution to the evolution of product data exchange standards, this time through its Product Definition Data Interface (PDDI) contract. The purpose of PDDI was to develop a mechanism to allow the complete exchange or sharing of product model data directly among computer applications - without human intervention. PDDI with its geometry focus, developed a set of information models, a modeling language that contributed to EXPRESS, an exchange file format that separates the data being exchanged from its definition, and a mechanism for applications to share data.