mystery dash light

A green light comes on between the service indicator lights and the fog light indicator. It looks like the turn signal indicator. <= => Local shops don't have a clue and neither does BMW service in Seattle. Any clue as to what it is?

1991 325i Convertible

Don,

TIA

I think this is the trailer indicator light. But usually there is no bulb when no tow hook is fitted.
Is it on constantly? with no bulb fitted the cluster is open in that compartment. Mybe another light source shining through? Is it fully lit up?