We have had SDF examples of a setting change which is smaller than the displayed resolution and so hidden by rounding. For example, I have changed a gain setting from its safe.snap value of 1.0 to 0.9999999999999998 and the SDF difference table shows both values being rounded to 1.000000. To get the actual value to 15 decimal places, use caget with the "-e 15" argument (without this argument it rounds to 1.0)

caget H1:PEM-MY_CHAN_17_GAIN
H1:PEM-MY_CHAN_17_GAIN         1
caget -e 15 H1:PEM-MY_CHAN_17_GAIN
H1:PEM-MY_CHAN_17_GAIN         9.999999999999998e-01
 

The snapshot of the table shows the two values are apparently the same when rounded to 6 decimal places.