[RichardJ]

>>Meter is the amount of holdoff of the front disc, to allow the rear drums to close up the running clearance.<<

True, but a residual valve and/or cup spreaders and well adjusted shoes take care of much of that.
Some vehicles are prone to nose diving at parking lot speeds with very light brake pressure. The metering valve or hold-off valve, holds back the pressure to the calipers and allows the rear drums to lightly drag.