Reference CSS Values and Units instead of specifying <length> in SVG (was: Re: Minutes, 15 jan 2015 SVG call)


A question to the units discussion:

> On Jan 15, 2015, at 10:33 PM, Chris Lilley <> wrote:
> <length> referenced to CSS is incorrect for SVG
>   Tav: length goes to css definition which is not ours, svg
>   differs on percent, unit identifiers etc
>   svg 1.1 already did that right
>   Tav: we need a two step definition for attrs and properties
>   ChrisL: this is different for svg attrs compared to properties.
>   it was right in svg 1.1
>   Rossen_: so it was right in 1.1
>   ChrisL: assume we want to refer to css3 values and units
>   heycam: i made some edits and split percentages from length for
>   comnsistency with css
>   ... the other part for unitless lenghts, not sure but may be a
>   mistake
>   ... to link directly, we have something in types that supports
>   unitless lengths
>   ... but css3 supports parsing of lengths without units in some
>   contexts so we should define it that way
>   ... invoke parser with that flag set
>   ChrisL: sounds like you know what spewc changes are needed
>   Tav: odd to click on length on rect and get that. its a
>   property. don't see that you dont need units
>   heycam: keep in types chapter, and then link to css spec there
>   whle talking about the unitless flag
>   <scribe> ACTION: heycam to fix length to point to types chapter
>   and flag unitless lengths [recorded in

I do not understand why it would be wrong to separate <length> from <percentage> and let both reference CSS Units and Values as it does in SVG 2 right now? Many of the attributes are presentation attributes now and we have to follow CSS grammar here. Don't forget that CSS defines more units than SVG has today and probably will define more in the future. It would be incompatible to CSS and wrong to do it as SVG 1.1 did and specify <length> any different.

There was one mentioning of unit less values for attributes. There is no need to specify anything in SVG 2 for that. CSS Syntax allows presentation attributes to omit units. There is no backward compatibility breakage here.

Do not change values and units back to the SVG 1.1 state but reference CSS where appropriate.


Received on Friday, 16 January 2015 13:57:14 UTC