This toggles 'graceful discard' for this circuit, a congestion-handling behavior where frames are dropped in a controlled, prioritized way -- discard-eligible frames first -- as the circuit nears its bandwidth limits, rather than an abrupt indiscriminate cutoff. An admin would enable this on circuits carrying a mix of critical and best-effort traffic so congestion sheds the least important frames first. For example, turning cktOde on for a circuit carrying both SNA and bulk FTP traffic ensures that during a burst above Bc+Be, the FTP frames marked DE are the ones dropped rather than the SNA session timing out.