Trailer wiring

Please can anyone enlighten me as to the meanings of these abbreviations on the pins of this relay? I think it’s gone faulty and was hoping to replace with a new one. Trouble is I don’t seem to be able to source a like for like too easily, so have ordered a universal one. I’m hoping it will replace the one here.

I think I figured out that +UB is permanent live and 31 is earth. AL is left flasher and AR is right flasher that go to towing socket.
This is on an 03 plate Land Cruiser that's had the towing pack fitted from new. I only need to get the basics going again. Not bothered about the caravan socket. The only fault is that the right hand flasher doesn’t work on the trailer board. Any information gratefully received. Cheers.

Heres a start https://shop.euroimpex.lt/en/dalis/383225/tow-bars-relay-(trailer-module)

I would have thought IL & IR meant indicator left & indicator right so I would check IR.

SOLVED!
A few weeks ago I’d moved the wiring loom out of the way whilst welding the rear cross member, I’d mistakenly plugged the towing loom back into itself and bypassed the cars indicator on the right hand side, thus it wasn’t getting the signal to activate the relay. Several hours later the penny dropped!!!