Nikola Smolenski wrote:

define('NBSP', "\xA0"); // iso-8859-x non-breaking space.

I've never witnessed that this is causing any trouble, but shouldn't it cause trouble on non-ISO Wikipedias? Shouldn't it be best that it is changed to " " which would work everywhere?

I don't understand your concern. *Especially* on non-ISO Wikipedias (i.e. UTF-8) it should not be a problem.