under e-tag 1.6, nerc implemented the "no tag, no flow" rule, where all energy transactions were to be documented with an e-tag. accurate system studies of the eastern interconnection in order to determine which schedules should be curtailed would only be possible if every transaction was tagged and therefore included in the idc calculations. reliability coordinators in the eastern interconnection could access the idc online and run flow studies based on various operating scenarios with all of the current energy schedules derived from the e-tags. when an actual contingency occurred, the reliability coordinators could identify the constrained transmission line or corridor within the idc, and the idc would then identify which e-tagged schedules should be curtailed in order to ease the loading on the restricted facilities.