How to map to "fade out" button on playback please ?

Hi, I cannot for the life of me find out how to map the fadeout button to my on-screen control - when I use the "map parameter" button and select the "fade out" button in the playback instrument, it maps to "play/stop (from start)". I cannot find fade out in any of the menu items under "playback".

What sorcery is required to fade out a track? If possible Id like the fade out to be triggered by pressing another control but I'll be just *** happy knowing how to trigger the fadeout please.

Im using 3.6.6 on Ventura. Thanks!