Chapter 5. MIME Types

GTKtalog uses MIME types to store the file types. So does Gnome, Kde ... The MIME type is determined by the extension or (best) by the content.

A MIME type is a string such as "application/zip" for (.zip files) or "image/jpeg" for (.jpg files)

In four places of GTKtalog, you are asked to type a Mime type (all in the preferences):

If you don't know the Mime string but you know the extension, use the button "Guess from an extension". Give an extension, it will return the corresponding Mime type .... cool !

If there is no known MIME type for your extension, you'll have to add it in the Gnome control center : Document Handlers/File types and programs. See the Gnome Control Center documentation for more information.