[Avid-L2] What Should be Legal Range and What should be Full Range in an HDR workflow?

I am running Avid/Resolve on a mid 2012 12 Core 3.46 GHz, 128 GB ram, Radeon RX-580 Saphire Pulse 8GB GPU.  I have the Avid branded DNxIO which feeds an Aja Hi 5 SDI to HDMI converter to trigger the HDR mode on my LG OLED C9.  I've had the LG OLED and my PVM-2541 professionally calibrated with the LG having separate calibrations for SDR and HDR.  I have confirmed with the calibration technician that the calibrations were done feeding legal level to the LG OLED.  They said that's how they always do it unless someone requests Full Range.  I realize in the higher end monitors like the Sony X310 you can set that the SDI input for legal (or they might call it limited) or Full Range but the LG to my knowledge has no such toggle.

Here are some of the behaviors I'm seeing:

In Resolve V16 and probably V17 as far as I know I can adjust the Data Level in the master settings to video or full for legal or full range to feed out of the DNxIO.  In order to do the trim SDR pass for Dolby Vision using the Target Display Output there is only one choice for 100 Nits and that is "100-nit, BT.709, BT.1886, Full".  Using this setting the Target Display Output follows the master settings Video Monitor Data Levels setting.  So setting Data Levels to Full yields a blown out SDR SDI signal with the level way below 0mV and way above 700mV.  Switching to Video Data Levels and the Target Display output is correct on an SDR Scope and monitor.

The Aja Hi 5 has a configuration Control Panel that has input and output level adjustments which they call SMPTE for Legal and Full for Full Range.  If feed a YCbCr SDI signal these controls are not functional.  I assume this is because in Googling I found that YCbCr is always Legal Range.  If I feed it 4:4:4 SDI then the input and output level controls function as expected.

In Resolve V16 and probably V17 when running in YCbCr mode, no check on 444 SDI in the master settings, I can still toggle the the Data Levels between Video and Full and I see corresponding jump in the SDI output of the DNxIO.  This seems to contradict what I found Googling regarding YCbCr always being legal or limit range.  Given the Aja Hi 5 has no level controls when feed YCbCr I assume I should choose Video level so that the Hi 5 YCbCr going in is legal.

The ultimate question is when outputting a file for Dolby Vision, targa or tiff sequence etc..., what should the video essence of the PQ material be Video or Full?  I'm told HDR is Full Range so I would guess that but then when doing the Dolby Vision Trim pass if I monitor while in Full range I get a very blown out Target Display Output which effects the trim pass and if I switch to Video Range output the Target Display for 100 nit looks more normal to start with.  I would think I should be in video mode to do the 100 nit Trim Pass using Target Display Mode but I am not certain of this.

So I am trying to find out what the video essence of the PQ ST 2084 level should be legal or full and if full then what is the 100 nit trim pass supposed to be done in Full or Legal Mode?

John Moore Barking Trout Productions Studio City, CA bigfish@pacbell.net