Re: [svgwg] Define all cases for intrinsic ratio

It looks like someone has done some re-writing since SVG 1.1, but this
 is an area that has been a historical problem for interoperability, 
so being extra clear is not a bad thing.

I agree with the red-text comments about changing the wording to be 
more consistent with CSS & the current spec.

The list of options skips over the case where _one_ of height or width
 is specified, but not the other.  This gets confusing when you get to
 the last paragraph, which seems to suggest that a used aspect ratio 
of 2:1 gets applied in that case.  Even CSS 2.1 as linked doesn't 
address the case where one dimension is specified by there is no 
intrinsic aspect ratio.  Which is perfectly possible in SVG.

We should update that link to point to [CSS 3 
images](https://www.w3.org/TR/css3-images/#default-sizing), which 
addresses this case by applying the default sizes independently to 
width and height, rather than by applying a default 2:1 ratio.

Additional things to clarify: 

- `width` and `height` are presentation attributes, therefore the 
important value is the used value for each, regardless of whether it 
is set as an attribute or via CSS. 

- If an SVG View is in effect, the intrinsic aspect ratio can change: 
need to use the used value of `viewBox` assigned by the view.

- Just because an SVG doesn't have an `intrinsic` height & width, 
doesn't mean height and width are undefined.  E.g., in many rendering 
contexts, percentage height & width do have meaning.

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Received on Monday, 11 July 2016 17:51:05 UTC