There is no such thing as .scj. However, there is .scm that is used by by Starcraft as a game map. .scm includes various types of terrain and resources and are created in different sizes, including 96x96, 128x128, 192x192, and 256x256.
Actually there is a .scj file format but only two PC games use it as far as we know. They are, Jurassic Park Dinosaur Battles and Jurassic Park Scan Command.
A compiled Help File in Windows will have the extension .chp
A console is saved in a file with an .msc extension.
Windows applications in general (not just for Windows 3.1) automatically append the file extension.
File Extension
file extension
The file name extension of clip art in Windows Clip Organizer is .jpg (JPEG).
Unix audio file.
.doc
.MSWMM
The extension. It tells Windows what kind of a file it is. For example, a file with the ".doc" extension is a Microsoft Word Document.
At the end of the file name. In Windows it's hidden by default.
File extension. Such as .docx, .wmv, .jpg