I'm confused by this shower mixer!

[theflyingpig]

Er, I think I'm missing something here! Can anyone help?

I've got this Bristan 2 outlet shower mixer, but no installation manual. I can feel that one knob controls the temp, and the other is the diverter, so can tell which way up it goes.... So can deduce which outlet is which....
But, how to tell which inlet is cold /hot? Can see H/C on the faceplate so assume that also indicates which side to plumb which?

And finally, the head scratcher.... What is the FIFTH threaded connector at the bottom for?

 

[stem]

You can find the instructions for it here.

 

[theflyingpig]

You can find the instructions for it here.

Thanks.

No mention of the fifth outlet... You can see it in their diagrams though.... Presume I just cap it off....