This is the RowStatus control column for a row in the zero-suppression table, which governs whether all-zero performance counter cycles are suppressed from being stored; per the source description, active(1) specifically means the suppress state is Unsuppressed for that entry. A network administrator manages these rows to control storage overhead from performance data that contains long runs of zero values. For example, an active row here for a given checkpoint type/cycle combination means zero-value performance data for that combination is currently being stored rather than suppressed.