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[csswg-drafts] [css-values] Retiring support for 3-valued positions (excluding background)

From: Eric Willigers via GitHub <sysbot+gh@w3.org>
Date: Thu, 28 Dec 2017 06:04:22 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-284847778-1514441061-sysbot+gh@w3.org>
ewilligers has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-values] Retiring support for 3-valued positions (excluding background) ==
The CSS [\<position\> spec](https://drafts.csswg.org/css-values-4/#typedef-position) changed early this year, so that 3-valued positions (`left 10% top`) would no longer be part of \<position\> syntax, for any properties other than background-position.

The change was accompanied by a motive:

> Note: The background-position property also accepts a three-value syntax. This has been disallowed generically because it creates parsing ambiguities when combined with other length or percentage components in a property value.

I added Blink use counters at the time, and we now have data.

[ThreeValuedPositionBackground](https://www.chromestatus.com/metrics/feature/timeline/popularity/2001) >1%

[ThreeValuedPositionBasicShape](https://www.chromestatus.com/metrics/feature/timeline/popularity/2002) 0.00004% ([spec](https://drafts.csswg.org/css-shapes-1/#funcdef-circle))

[ThreeValuedPositionGradient](https://www.chromestatus.com/metrics/feature/timeline/popularity/2003) 0.001% ([spec](https://drafts.csswg.org/css-images-4/#valdef-conic-gradient-position))

[ThreeValuedPositionObjectPosition](https://www.chromestatus.com/metrics/feature/timeline/popularity/2004) 0.00007% ([spec](https://drafts.csswg.org/css-images-3/#propdef-object-position))

[ThreeValuedPositionPerspectiveOrigin](https://www.chromestatus.com/metrics/feature/timeline/popularity/2005) 0.000001% ([spec](https://drafts.csswg.org/css-transforms-2/#perspective-origin-property))

All of the main browser engines still support 3-valued positions as <position> values (apart from Edge for perspective-origin, but it doesn't accept 4-valued perspective-origin values either).

Does the Working Group ratify the retiring of 3-valued positions (excluding background)? Are browser vendors in agreement to remove support?

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2140 using your GitHub account
Received on Thursday, 28 December 2017 06:04:34 UTC

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