IGES (Initial Graphics Exchange Specification) was among first vendor-neutral CAD formats designed to enable interoperability between different CAD systems. The latest versions of IGES have been approved by ANSI (American National Standards Institute) and published by US PRO (U.S. Product Data Association). The latest officially approved version of the IGES standard is version 5.3 which was published in 1996. Nonetheless, IGES remains a broadly used format (along with STEP) supported by all major CAD/CAM/CAE systems such as CATIA, Autodesk Inventor, Solidworks, Solid Edge, NX, Pro/Engineer, Creo and multiple others. IGES files usually have *.igs or *.iges file name extensions.

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In solid modeling and computer-aided design, boundary representation—often abbreviated as B-rep or BREP—is a method for representing shapes using the limits. A solid is represented as a collection of connected surface elements, the boundary between solid and non-solid.

Boundary representation of models are composed of two parts: topology and geometry (surfaces, curves and points). The main topological items are: faces, edges and vertices. A face is a bounded portion of a surface; an edge is a bounded piece of a curve and a vertex lies at a point. Other elements are the shell (a set of connected faces), the loop (a circuit of edges bounding a face) and loop-edge links (also known as winged edge links or half-edges) which are used to create the edge circuits. The edges are like the edges of a table, bounding a surface portion.

Compared to the constructive solid geometry (CSG) representation, which uses only primitive objects and Boolean operations to combine them, boundary representation is more flexible and has a much richer operation set. In addition to the Boolean operations, B-rep has extrusion (or sweeping), chamfer, blending, drafting, shelling, tweaking and other operations which make use of these.

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