After reading this and other DCP-related threads, I am still wondering whether there is a universal answer to the following question...

Workflow is basic: Alexa -> DIT -> DNxHD115 MFX-Files -> Editing

For a screening in a local theater a DCP is needed which will be made at an external facility. All I have to deliver is a same-as-source quicktime. So fortunately no science needed from my side, but still one setting to set:

"Keep as Legal Range" or "Scale from Legal to Full Range"

From what I have understood I would guess that there is no right or wrong because it depends on how the DCP-software interprets my file. Or is one of the two options fail-safe? Maybe fail-safe regarding color-levels (more important in my case), even though it might involve unnecessary conversions (less important in my case)?

Of course, I will ask this facility for this presentation. But just in case I got it wrong and there is a rule of thumb, then that might come in useful some other day. Like when you have to deliver at 8 am, start your export at 5 am and you realize "Oops, forgot to ask that one question..." ;)

If I missed the answer to my question in one of the other threads, don't hesitate to just point me there. I will re-read it thoroughly. :) 

Cutyes:

"Keep as Legal Range" or "Scale from Legal to Full Range"

Ask the facility, but in general, I would stick to "keep legal" as that will not change any luminance levels. The DCP authoring software will need to be told that it is being fed a Rec709 legal video as source.