xdgurl (install helper program for desktop stuff)

XDG-URL  is a custom URL that represents the installation  method  of
desktop stuff.

Just click an XDG-URL link, or type XDG-URL in browser's address bar.

If you use Firefox, a program  selection window opens the  first time
you open XDG-URL, and you can choose "xdgurl" as custom URL handler.

If you don't get the program selection window or you are using 
another browser, please set the xdgurl program as custom URL handler
for xdg:// scheme in the browser's settings.

From CLI, execute xdgurl program with argument XDG-URL:

 $ xdgurl "XDG-URL"