used for virtual keyboard entry, like backspace key on keyboard (I assume). I can't remember where I found that out - I only ever used it as a meaningless entry to stave off the screensaver!
Oh, you meant ECP? Genius! Here, i collected some codes:
/keypress/Backspace = 11
/keypress/Search = 12
/keypress/Play = 13 'also PlayOnly by default
/keypress/Enter = 15
/keypress/PlayOnly = 22 'when `playonly_aware` manifested
/keypress/Stop = 23
/keypress/VolumeUp = 24
/keypress/VolumeDown = 25
/keypress/VolumeMute = 1114113 '0x110001
/keypress/ChannelUp = 1114134
/keypress/ChannelDown = 1114135
/keypress/Sleep = 1114138
/keypress/Game = 1114139
Btw @RokuMarkn - while exercising above, seems somehow i wedged the player into a bizarre state, in which the Home button won't work (by physical remote or ECP), while all the other remotes did work. Ultimately i had to power-cycle it.