@johnpallett: Can't add you as a reviewer directly, but could you take a look at this?

Thanks for the feedback, John! Left some responses and made some tweaks.

Are we comfortable that this approach gives sufficient direction to implementers? ...

This has been my primary source of angst around this text. (And #761, to a slightly lesser degree.) It comes down to a couple of things, I think:

• There's some of these privacy principles that must be validated at runtime (are you visible and focused?) and those slot well into spec algorithms. Then there's other limits that feel more like intrinsic properties of the implementation, and as such it sounds extremely weird to ask for it to be validated in an algorithm. (ie: "If the pose will not be sufficiently rounded to prevent fingerprinting return null and abort the rest of these steps." Um, no? Because if you're not doing that then it just mean's you're not a valid implementation?) It's not as clear what the appropriate mechanism is to surface those kind of behaviors is.
• Some of this content could/should be moved up in the document to be closer to the definition of the mechanism in question. Like, we could move the bounded-floor bounds limitations up into the section dedicated to discussing that interface easily, and it would likely read well. I worry that doing so may dilute the overall privacy message, though? When you have all of the privacy-centric dicsussion in one place like this it helps sell that it's important and gives a better mental picture of how all the limits relate rather than just being a jumble of somewhat confusing lines scattered throughout the doc?

If you have any thoughts on how to ease that tension, I'm happy to hear it!

Moved the reference space requirement bullet points around to the appropriate contexts and/or made them part of an algorthim. This feels like it "dilutes" the privacy-centric portion of the doc, because now some privacy driven limits are scattered throughout the doc, but it is probably easier for implementers this way and ultimately that's what counts.

Thanks for the review! Made a partial update to hit some of the simpler changes. I'll get the remaining change on or before Monday.

Okay, everything should be addressed one way or another now. PTAL!

Nits addressed. Thanks!