Paper White Nits value for "Rec2100-PQ -Display"?

Hey, sorry for the newbie quesiton.
Using the cg-config-v2.1.0_aces-v1.3_ocio-v2.3.ocio config, I output to Rec.2100-PQ - Display from a input color space of Linear Rec.709 (sRGB), un-tone-mapped.
If I send a texture that is all (1, 1, 1) into this, I get a output value of 0.508, which seems to imply to me it’s treating (1, 1, 1) as 100 nits, rather than the 80 nits I’m reading should be expected for this conversions.
Can anyone illuminate what is happening here?
I’ve searched around for the past few hours but unable to find the right doc that explains this.