The 3D ACIS Modeler (ACIS) is a geometric modeling kernel developed by Spatial Corporation (formerly Spatial Technology), part of Dassault Systemes. ACIS is used by many software developers in industries such as computer-aided design (CAD), computer-aided manufacturing (CAM), computer-aided engineering (CAE), architecture, engineering and construction (AEC), coordinate-measuring machine (CMM), 3D animation, and shipbuilding. ACIS provides software developers and manufacturers the underlying 3D modeling functionality. ACIS features an open, object-oriented C++ architecture that enables robust, 3D modelling capabilities. ACIS is used to construct applications with hybrid modeling features, since it integrates wireframe model, surface, and solid modeling functionality with both manifold and non-manifold topology, and a rich set of geometric operations. History As a geometric kernel, ACIS is a second generation system, coming after the first generation Romulus. There are several versions about what the word ACIS actually stands for, or whether it is an acronym at all. The most popular version is that ACIS stands for Alan, Charles, Ian's System (Alan Grayer, Charles Lang and Ian Braid as part of Three-Space Ltd.), or Alan, Charles, Ian and Spatial (as the system was later on sold to Spatial Technology, now Spatial Corp). According to a close source the name actually stands for Alan, Charles, Ian, Sowar, with Sowar coming from Dick Sowar, founder of Spatial Technology. However, when asked, the creators of ACIS would simply suggest that its name was derived from Greek mythology (See also Acis). In 1985 Alan Grayer, Charles Lang and Ian Braid (creators of Romulus and Romulus-D) formed Three-Space Ltd. (Cambridge, England) which had been retained by Dick Sowar's Spatial Technology (which had been founded by Sowar in 1986) to develop the ACIS solid modeling kernel for Spatial Technology's Strata CAM software. The first version of ACIS was released in 1989 and was quickly licensed by HP for integration into its ME CAD software. In late 2000, around the time when Spatial was acquired by Dassault Systemes, the ACIS file format changed slightly and was no longer openly published. Architecture A software component is a functionally specialized unit of software—a collection of software items (functions, classes, etc.) grouped together to serve some distinct purpose. It serves as a constituent part of a whole software system or product. A product is one or more software components that are assembled together and sold as a package. Components can be arranged in different combinations to form different products. The ACIS