Calrec PCB Question

I have got the old pencil and graph paper out - having a look at the Calrec EQ and trying to upsize it manually (and understand from a newbie perspective what is going on - the relationship of the schematic ti the layout etc...)

Just one question that my simple brain is struggling with...
On the Rev 4 of the Gyraf PCB
http://www.gyraf.dk/gy_pd/calreq/calreq.pdf
On the second PCB - the HMF and HF one
Underneath the HF Hi Q switch is a grounded area...
Ground and Left pin 2 of the Shelve switch got to a 100k pot and then into this area... and then nowhere else...
Why is this?
I was drawing the PCB on the graph paper and wondered why the circuit stops there and doesn't have a jumper into one of the other ground areas...

It doesn't go anywhere on the schemo, it's just setting up a parallel resistance or not. The signal won't disappear!

many thanks Jonathan