Why HTML5 dates are not simply ISO 8601

Notes from a 2009 WHATWG discussion about date formats, invalid input and why HTML needs more precise parsing rules than ISO 8601 alone.

Published

Er, why doesn’t HTML5 just use ISO 8601?

Why the HELL have they gone and invented their own datetime specification?

Several reasons:

Thanks to #whatwg guys for informing me. Again.

The same reasoning could be applied to XSD dates.