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Re: [css3-animations] Times are listed as unitless

From: Eric A. Meyer <eric@meyerweb.com>
Date: Sun, 1 May 2011 23:28:46 -0400
Message-Id: <a06230902c9e3cfcccd09@[10.6.62.125]>
To: www-style@w3.org
At 17:21 -0400 5/1/11, Boris Zbarsky wrote:

>Where are these expectations coming from? 
>http://www.w3.org/TR/1998/REC-CSS2-19980512/syndata.html#q20 (CSS 
>2.0, back in 1998) says that times can't be unitless.  Compare it to 
>http://www.w3.org/TR/1998/REC-CSS2-19980512/syndata.html#length-units 
>which says that 0 lengths can be unitless.
>
>Or is the expectation coming from the fact that most web authors 
>never used any times, only lengths, which don't have the same 
>syntax, and now they're starting to use times and being confused?

    Very much so, yes.  For well over a decade now the lesson (not 
from the WG or specs, but in the general community) has been "zero 
needs no unit".  Not "zero lengths need no unit", just that zero can 
always be unitless.  Now that other number-based value types are 
coming into use-- almost nobody ever used time values in the past-- 
most authors will assume they can have unitless zeroes everywhere. 
And the allowance for 'rotate(0)' isn't going to do anything to clear 
up the confusion.
    It's going to be an educational challenge, but there should enough 
to make the explanations fairly clear.  Thanks for the pointer to 
that thread, by the way.

-- 
Eric A. Meyer (eric@meyerweb.com)     http://meyerweb.com/
Received on Monday, 2 May 2011 03:29:12 GMT

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