.S File Extension

Generic source code file that contains the source for a computer program; may be written in a number of different programming languages; can be opened and edited with a text editor.

Shape file used by Microsoft Train Simulator, a program that allows users to play the role of a locomotive engineer or passenger; contains shape data such as geometry, images, size, texture, and lighting effects; used for customizing and displaying locomotives in Train Simulator.

S files can be used to "tweak" new locomotive graphics that are added by users. They can be generated using the "Conv3DS" program with .3DS files in Train Simulator. Once an S file has been generated, it may be edited using a text editor.