Today I became aware of the ECMAScript Internationalisation API, as I was researching a sane way to format numbers. Thus I tested for German by calling
Intl.NumberFormat("de").format(10000.23)
on the console in Firefox and Chrome, which provides me with "10.000,23".
However this form of number formatting is discouraged in German according to the DIN 5008 standard (and the official language reference "Duden"), which says that thin spaces (\u2009) should be used as a thousand separator.
Who defined the use of this thousand separator for German localisation? The Unicode Consortium or the browser vendors?
(Yes, I am aware that some programs and persons may use the dot as German localisation approach)