.OPT
.OPT files are the 3D format in which all objects in X-Wing Alliance, X-Wing vs. TIE Fighter, Balance of Power and the '95 versions of X-Wing and TIE Fighter are made in, ranging from the craft to the lasers and warheads. Besides the actual 3D model, an .OPT also includes the Textures and some of the Properties of the objects. As such the likely meaning of .OPT might as well be "Object, Properties and Textures".
There are two formats of OPTs: the X-Wing vs. TIE Fighter format and the X-Wing Alliance format. The X-Wing vs. TIE Fighter format is the older format also used in Balance of Power and the ’95 versions of X-Wing and TIE Fighter, the X-Wing Alliance format is more advanced and only used in that game. While very similar, you cannot use one format as the other or vice versa. The game will generally not crash but your lighting and textures will look very trippy indeed. The XvT format OPTs can be found in your “ivfiles” folder, the XWA format OPT are stored in your “flightmodels” folder.
By editing or creating the .OPT files for the X-Wing Series games you will be able to create new craft, new weaponry or completely new planetary objects which can add just that extra touch to a mission or battle. In principle you could even change the whole game to make total conversions.
The Imperial Academy offers a course on how to make your own .OPT files: the OPTing Course
