[round-display] [motion-path] Orientation of elements due to merging polar positioning and motion path

I was thinking about our resolution from last week to merge the polar positioning properties from CSS Round Display[1] into the Motion Path[2] properties.

The spec of CSS Round Display describes polar positioning as a way to position an element. It doesn’t seem to mention the orientation of the positioned element changing at all. This is consistent with the green box in drawn in Example 8[3].

However, this is not true of motion path. In motion path, Example 1[4] shows the orientation of the airplane changing to face the path.

According to the text of the “motion-rotation” property[5], the polar-angle behavior can be achieved with “motion-rotation: 0deg;”. However, the syntax here doesn’t agree with the values’ explanation in the spec text - the syntax should be:
“[[ auto | reverse ]? <angle>?]!”

Given that rectangular displays are much more common on the Web than round displays (and this will likely continue to the the case into the far future), the default behavior should be the motion path behavior. Therefore, the default value after the merge should be “auto”.

Thanks,
Myles

[1] https://drafts.csswg.org/css-round-display/ <https://drafts.csswg.org/css-round-display/>
[2] https://drafts.fxtf.org/motion-1/ <https://drafts.fxtf.org/motion-1/>
[3] https://drafts.csswg.org/css-round-display/#example-5f4258fe <https://drafts.csswg.org/css-round-display/#example-5f4258fe>
[4] https://drafts.fxtf.org/motion-1/#example-11b4e424 <https://drafts.fxtf.org/motion-1/#example-11b4e424>
[5] https://drafts.fxtf.org/motion-1/#motion-rotation <https://drafts.fxtf.org/motion-1/#motion-rotation>