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Re: [CSS3-mediaqueries]: Invalid test cases in test suite

From: Chris Lilley <chris@w3.org>
Date: Thu, 29 Sep 2011 22:36:44 +0200
Message-ID: <1359891026.20110929223644@w3.org>
To: Arron Eicholz <Arron.Eicholz@microsoft.com>
CC: Boris Zbarsky <bzbarsky@MIT.EDU>, "public-css-testsuite@w3.org" <public-css-testsuite@w3.org>
On Thursday, September 29, 2011, 6:22:23 PM, Arron wrote:

AE> On Wednesday, September 28, 2011 1:24 PM Boris Zbarsky wrote:
>> On 9/28/11 4:13 PM, Arron Eicholz wrote:
>> > CSS 2.1 still doesn't cover 0 exactly. What is 0?

>> The CSS 2.1 spec says its numbers are real numbers.

AE> But what is a real number to CSS? There is no reference from the
AE> CSS spec to go off of for real numbers. 

Hopefully CSS WG will not redefine real numbers.

AE> Again I am asking for
AE> reference or us being explicit about 0 and +0. Maybe we need to do both.

I think that is mixing levels (syntactic and semantic levels).

AE> You are correct that we say real numbers but the spec doesn't say
AE> if 0 is included in positive or negative numbers (for example when
AE> we discuss property values that take positive numbers).

In terms of semantics, zero is neither positive nor negative.
http://en.wikipedia.org/wiki/Zero#As_a_number

In terms of syntax, CSS allows "0" or "-0" or "+0" and these forms all result in the number zero.

So if the intent is to allow zero, one etc then 'non-negative numbers' is the phrase to use.

>> -0 is equivalent to 0 and is not a negative number. +0 is
>> equivalent to 0 and is not a positive number. 0 is neither positive nor negative number.

Yes.


-- 
 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Thursday, 29 September 2011 20:37:04 GMT

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