[Follow-up report]
Dial gauge showed [unit in 0.01mm]
while vacuum measure showed 15 mbar at 14:36 and 12 mbar at 14:49.
More explanation
This is just my otsukai, but as far as I heard, there are three dial gauges set at the chambers; two for the PR3 chamber and one for the PRM chamber. At the bottom of PR3, close to the legs, one dial gauge is set, while there is another dial gauge at the top of the PR3. One dial gauge is also set at the top of the PRM chamber.
Oh, I'm sorry that I misread; the smaller circle in the gauge had that meaning!