This read-only integer (1..65535) reports the round-trip delay in milliseconds measured the last time the testdelay option of chanTestType was run on this connection. An administrator reads it after triggering a delay test to quantify actual latency across the connection rather than just confirming continuity. For example, after setting chanTestType to testdelay and waiting for the test to finish, an engineer would read chanRTDResult to see the measured round-trip time in milliseconds for that specific channel.