The 10 day trends attached around the April vent show the change in HAM2's position sensors cartesian location.  The middle panels show the pressure and gaurdian request state.

At the beginning, the HAM remained locked through the venting and then was taken to DAMPED.  Clear shifts in position are seen at that time.

This table is the position in the two states:

DOF      Isolated/vacuum     Damped/vented
Z         -39800nm                 -20 -- -17um
Y         -57000                        -61.5um
X           4300                           15
RX         26000                        26.3
RY        -33400                       -19.5
RZ         85800                        86.3 -- 88.5
 

This vent was short, about 2 days and the observant reader will notice the range in the above table for Z and RZ along with the trends for these DOFs moving during the vent period.  I'm guessing this trend is the continuing thermal transition after coming to atmosphere.  After pumping down, the ISI remained unisolated for a few more days and the positional change between at atmosphere vs at vacuum is evident.  Finally, the ISI is reisolated back to where it started.

The important point is the Isolated versus vented position.  At atmosphere, the ISI would be stopped on the lockers if work were to be done and we strive to have that shift between locked/unlocked to be less than 50um local coordinates.  The locking is usually a bit better than this.

During at-atmosphere work, these LOCATIONMON channels will give an indication of position changes with the caveat that all references are on the slab.