Hi gents/ladies...
I am putting back together a S3 with a defender engine (2.5TD) for my old man, he has partly assembled this, but is struggling.

Can anyone identify a port on a CAV DPS pump for me?
This is the pump fitted to a 2.5TD

On the inboard side there is a small port, the treads are clear and clean as if something should be there and is missing, i have no idea what this is for - any help/comments appreciated.
If the attachment can be read it is the text box in yellow.
ATTACHMENT HERE
Cheers
Tony

if its a blind hole ,nothing

Rear four unions have the injector pipes, rear vertical Union has fuel in from lp pump, front Union( nearest flange) is return pipe, links to injector leak of pipes, either goes back to filter or tank

It connects to nothing.