missing vac hose behind plenum?

[ashc]

Whilst peering behind the plenum contemplating my up and coming attempt at redoing my ratsnest, i noticed one of the small metal pipes doesnt have a hose attached - i presume it isn\'t required because the car runs fine but i would like to know what it is - i can\'t fathom it out from the vacuum hose diagram in the workshop manual :3Confused
it doesnt bode too well for my ratsnest replacement job - i need to learn more first!! :o  
heres a pic but hard to jam my camera down behind the plenum so not very clear.

[probedb]

Yep there\'s a couple that don\'t....find the vac diagram and it\'ll show you which aren\'t there I think one is for auto cars, the other for something the US peeps have that we don\'t.

[ashc]

thanks! thought it might be something like that!