The TREF Decision

Are we really listening to our users?

A short history

• 2009: Resolution to expand <tref> use.
• 2013: Email discussion on removing <tref>
• Philip Rogers: Proposes to deprecate <tref>
• David Dailey: How to animate text content declaratively?
• Tab Atkins: Animate 'display' on <text>
• David Dailey: Should work and gives example.
• Rick Graham: <tref> useful for shadowing text, used in air traffic control industry to ensure readability of text.
• Doug: Argues against deprecating, suggest same security model as <use>.
• Dirk: Agrees(twice!).
• Manuel Strehl: <tref> useful for localizatin with remote server.
• Philip Rogers: <tref> use is rare.
• Manuel Strehl: Low use is due to Firefox not supporting it. He's been waiting for them.
• Thomas: Reminds us that SVG is used outside of HTTP.
• Doug: Proposes keeping as it is used in technical drawings.
• Philip Rogers: <tref> use is rare but if same security model as <use> is used, implemenation problems go away.

Is <tref> useful?

Two use cases reported:

1. Shadowing text.

   Two or three other ways of shadowing text:

   • Use <use>
   • Use 'paint-order' with stroke behind fill (already supported in Rick's targeted browser).
   • Use 'mix-blend-mode' with 'difference' value.
2. Reference localized text from server.

   Don't know details.

Breaking content

Removing <tref> (not even deprecating) breaks content. Rick Graham reports that they have existing installations for air traffic control that use <tref>, relying on internal Java based browsers for actual air traffic control but mirroring display on Chrome based browsers.

Statistics don't count if it's not implemented broadly

You can't properly guage demand if a feature isn't widely implemented. People don't want to produce broken web pages.

should we remove tref from SVG2?

erik: It is not implemented in Firefox. There is not much use in blink. People are looking to remove it if possible.

Rich: Is it implemented in IE?

nikos: Not implemented in IE11

erik: You can use the <use> element instead so not much loss of functionality

nikos: if <use> satisifes those then we will be ok

ed: tref can be used inside a text element. but use you would use outside but you can mostly do the same thing

<nikos> http://lists.w3.org/Archives/Public/www-svg/2013Jun/0075.html

nikos: There was some comment about it breaking air traffic control software
... it was a little bit vague
... If it is not really implemented in browsers anyway …

ed: there were a lot of quirks with it so I would like to remove it. It makes things more complicated for implementation
... If you have script you can do anything with it but there is not always the opportunity to use script
... I propose that we try to drop it with the next publication of the spec.
... hearing no objections

RESOLUTION: Remove TREF from the SVG 2 spec.

Previous <tref> resolution

CL: I propose removing within an SVG document fragment part

<ed> xlink:href for tref says:

<ed> A URI reference to an element/fragment within an SVG document fragment whose character data content shall be used as character data for this 'tref' element.

<ed> change to:

<ed> A URI reference to an element whose character data content shall be used as character data for this 'tref' element.

RESOLUTION: We agree to remove the restriction of tref pointing to only an SVG document fragment