Global Standards for the Microelectronics Industry
centerline
A reference line on a control chart about which the chart points are expected to cluster in the absence of a special cause. It is usually set at the average, median, or mode of the points being plotted, or (for a tunable process) at an achievable target value (to detect deviations from the value thought most desirable).
References:
EIA-557-A, 7/95