[For anyone reading this thread, make sure you read the last post - this information is incorrect.]

The EOTF in the extended area (i.e. above the legal value) is not correctly computed.
You can see from the snapshot (a Rec709 case) that the selected point has been modified to have more luminance than expected, but gamma is above 2.4 (worthless to say it should be below). That happens on all the point above the legal value. I have done the same on a measurement in the legal area, and (obviously) everything works fine.
I remember I was told that the EOTF in the extended area is approximated as a line. It looks like there is somewhere a sign error when computing EOTF from that approximating line.

Eotf on the opposite sign

Sorry, but without detailed information on what you have done, we can't even guess what you are trying to show...

Steve

What I have done (i.e. how I have outlined the issue), is irrelevant.
Anyhow, all the details are in the bcs file, which has been created using CS. Check EOTF in the extended (> legal level) zone.
You have that following Actual Y > than 2.4 target, the measured EOTF is >2.4. That looks wrong, doesn't' ?

Attached file: bcs file

Sorry, but from what I can see all is plotting as expected, based on the point readings.
I really do not understand what you are trying to show as being incorrect?

Steve

Ok - I do now understand what you are trying to say, but you are incorrect...

EOTF has nothing to do with the Y value, but is effectively the 'angle' through the point, and that is what the Dif EOTF Graph is plotting, and what the EOFT values show.
(That is why zero and 100% cannot have an EOTF value.)
The plots, and the the reported EOTF values, are indeed totally correct.
(The error is actually with your understanding of EOTF.)

Steve