Modulus operator & division by values

Hi,

I've recently come across a use case where the modulus operator would have
been useful[1], so I was wondering what were the reason which led to its
eviction from the current spec. I have been able to find the following
discussion[2], but I'm not sure to fully understand the argument :

 1. We drop the 'mod' operator since it only makes sense when
    both operands have the same units.

In my fiddle, you can see that I'm using a 'px' modulus on a percentage,
and I think it makes perfect sense after converting the percent into a
pixel unit (which is probably delayed up to the rendering ?).

Am I missing something ?

[1] http://jsfiddle.net/bBESS/4/
[2] http://lists.w3.org/Archives/Public/www-style/2010Jul/0442.html

-- 
Maël Nison