W3C home > Mailing lists > Public > www-style@w3.org > February 2004

Re: [css3-values] unit equivalence (was: [CSS21] response to issue 140b)

From: David Woolley <david@djwhome.demon.co.uk>
Date: Sat, 14 Feb 2004 13:29:31 +0000 (GMT)
Message-Id: <200402141329.i1EDTVS05428@djwhome.demon.co.uk>
To: www-style@w3.org

> Actually, I would have to say that in the context of CSS, it would
> be best to not require that 1cm = 10mm exactly.  Here's why:

I think that CSS should favour the user in this context.  Most users
won't have read the specification or appreciated the subtlety, so
will be upset if some implementations cause two constructs to be
a pixel off because one was spaced as a large number of mm widths
and the other one as a single cm width.

More of a problem here is that the individual mm widths probably
get rounded to pixel boundaries, which will encourage people to
use pixel widths, when these are the worst units to use from 
media independence and accessibility points of view.

> same as 13mm for the same reasons that 1.3 * 10 might not equal
> 13 on a binary computer.

Doing arithmetic in decimal doesn't seem a great hardship.  If you want
to speed it up internally, for repeated uses, you can always convert to
rational binary (13/10).
Received on Saturday, 14 February 2004 08:45:43 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 27 April 2009 13:54:26 GMT