ReadonlyFormReadonlyNodeReadonlyNumericWhether the cap is plain integer literals (no expression, parameter, PERCENT or WITH TIES).
ReadonlyPercentReadonlyRowsRows kept; null when not a plain integer, or for LIMIT ALL and OFFSET.
ReadonlySkipRows skipped, for OFFSET and LIMIT m, n; null otherwise or when not a plain integer.
ReadonlySpanReadonlyWith
One row cap the top-level query expression carries.