Is there a tutorial or explanation of what each of these files do in Mapsource?
"app_mdr.img", app.img, app.mdx, app.tdb ("app" is the application name eg "CNNA2008")

Maps do not show correctly if the files are missing or generated by Mapset tool kit.

Sorry if this is already explained in the forum, but in a search I did not find any information about what these files do.
Thanks for any help.