Editing DAT files
If you are looking for an article tha exaplains how to edit levels, read level editing. This article explains how to handle with generic dat files, as for example extracting graphics, sounds, levels, etc.
The program that we'll use to extract dat files is PR. It plays a role like tar in .tgz files or pkzip in .zip files.
TODO: someone to copy the sourceforge howto's articles here.