gearbox sensor???

as title i asked before but didnt reall get a definitive answer,my brothers 98 1.8 2 door fl without hill descent/abs/traction control,on the front of the gearbox below the clutch slave cylinder there is a sensor type thing its broken off,what is it? what does it do? it doesnt seem to affect the car in anyway,but i presume its there for a reason but what? any help please as he needs to order one but kind of hard when you dont know what to ask for!!!!

Post a picture, it might help

It sounds like the first gear switch for hill descent if it's below the reverse light switch and slave cyl. As he doesn't have hill descent perhaps its just a blank??
Or maybe it's not the original gearbox and it has been sourced from one with hill descent. Either way, don't worry about it.

thanks for the replies,it is wired up and the connector is broken off,if it was another box why would they connect the wire on? it defo aint just a plug!! what your saying makes sense ive ordered the workshop on disc so hopefully that will explain cheers anyway