UNIFIED DATA FORMAT IN CAD SYSTEMS
The main problem of data transmission unification is assurance of content consistency for information objects. Data consistency is necessary for development of a subsystem in integrated information systems. The analysis completed by the authors demonstrates that there is no data exchange format in CAD systems covering the whole variety of data to be transmitted via the communication channel. Therefore, STEP protocol (Standard for) (provided by international standard ISO 1030) is proposed for data transmission unification. The protocol determines a neutral data format realized through the product information model. This model incorporates the elements and the configuration of the product, different geometrical models, administrative and special data. All data are described in STEP using object-oriented language EXPRESS similar to the programming language. Access to EXPRESS data is provided by standard methods. EXPRESS language is designated for the conceptual description of the model. Global description is split into subject domains, or schemes. The information model represents interconnected schemes. A scheme consists of a set of elements that may include entities, types, constants, rules, functions and procedures.