The following is a picture of my brake master with ports labelled.
The top 3 I know where they go.
The bottom one (number 4) is one that I have no idea of, is one that can / should be blocked of and / or where does it go to.

Also you can see the bottom of my brown coloured bottle, it seems you cant replace them so I was thinking of making a custom one, has anyone had a go at this our sourced one ?

Thanks Gavan

 

Isn't that the one the braided hose attaches to?

Can't be 100% certain but I'll have a look tonight

 

theres notbing connected to that on mine.

 

Thanks for the replies
Its thread looks like it had something in it, but if you don't have anything on yours then it must just an area that did not corrode.
I dont know of a braided line attaching there, where would it go to ?, the manual does not say anything about it either.