[Trigon.]

Thanks mz. Yes, I'd quite forgotten that the 6306 programmer's manual covered that response.

So the question is what am I seeing? At first I thought the calibration data might be corrupted, but then checksum should have failed and the response would be 'CAL OFF'...

Does your unit return the documented response?

As I was concerned about the calibration data I ran self-test Program 9 which displayed:

1.0003
1-1
CAL

The rotary control cycled through 6 pages:

1.0000
1-2
CAL

0.9984
1-3
CAL

1.0000
1-4
CAL

1.0000
1-5
CAL

1.0000
1-6
CAL

Which seems like quite plausible calibration data.

Cheers