This read-write object, ranging from 1 to 5, sets the percentage of clock frequency deviation, for X.21/V.35/HSSI DTE interfaces, that triggers a clock rate out-of-bound alarm, and is supported on FRSM-HS2 and FRSM-HS2/B cards. An administrator tunes this tolerance to control how sensitive the clock monitoring is to rate deviations from the expected frequency. For example, a link known to have a slightly unstable external clock source might use a higher threshold value to avoid nuisance alarms.