[citation needed] 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.

In late 2000, around the time when Spatial was acquired by Dassault Systèmes, the ACIS file format changed slightly and was no longer openly published.

The two formats store identical information, so the term SAT file is generally used to refer to either when no distinction is needed.

A SAT file contains carriage returns, white space and other formatting that makes it readable to the human eye.

SAB files cannot be viewed with a simple text editor and are meant for compactness and not for human readability.

This allowed external applications, even those not based on ACIS, accessing the data stored in such files.

Thus reading of modern SAT files requires either using native ACIS library or reverse engineering of the format.

Beginning with Release 7.0, ACIS started again providing accurate major, minor, and point version numbers.

To summarize how release numbers and SAT changes are related: In 2023 Alibre Design, BricsCAD, SpaceClaim,[5] TurboCAD, Cimatron, Viacad, SharkCad and Vertex all used ACIS as their geometric kernel/engine.