110107-0942 EST
Non-critical means non-critical. Moderately obvious. If a resistor value was critical it would mean the preciseness of its value would be important. If it was specified as 151.6 kohms, then it is likely that without a specific tolerance value that this resistor might need to be within +/-0.5 kohms or better. A resistor specified as 10 k +/-10% would be relatively non-critical.
See figure 21 of
http://focus.ti.com/lit/an/sloa096/sloa096.pdf for a non-critical reference. R5 and R6 form a voltage divider. There values could probably range from 10 k to 1 meg so long as both were close to the same value. I did not see anything on how accurate their ratio needed to be, but one could not be 10 k and the other 1 meg.
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