We're working with some custom AOVs and I'm wondering if anyone knows what determines the order of the render vars in the Render Outputs dropdown in the viewport as well as which rendervar ends up as rgba when opened in nuke?
Is there some sort of ranking order, creation order, alphabetical pattern, attribute aso that we need to follow in order to control this?

I'm having a hard time figuring out a pattern.

For example I would like to name our "beauty" either beauty or preferable rgba and always have it at the top of the list in render outputs and be the primary selection when kicking off a new render and also become the rgba channel in nuke.

We currently have a bunch of other aovs like albedo, LIGHT_light1, LIGHT_light2, depth(Z) aso
and it seems like the sorting in the dropdown is arbitrary and LIGHT1 ends up in the rgba channel in nuke.
See attached image 1.

Even using the karmarendersetting nodes render vars it seems the list order is arbitrary. See attached image 2.

In H20.5 the "rgba" rendervar worked in nuke and became the primary channel but in H21 the same naming is no longer working, I'm assuming this has to do with the H21 redesign of the rendervar node.

Any help in how we can control this or what rules we need to follow would be highly appreciated.

We are using H21.0.512 on windows 10 in case that matters.

Add your preferred rendervar first in the list, then use wildcard for the rest.