[xml] ISO 8601 date support?

["Erik F. Andersen" <ea ascott dk>]

Hello all!

I need to convert a date to the format specified in http://www.w3.org/TR/NOTE-datetime and I wonder if there 
is a set of functions (in LibXML2) to do this?

The function must take a date (any date) and return a value on the form 1994-11-05T08:15:30.000-05:00.

The TZD (time zone designator) must be calculated with respect to daylight savings for the particular date in 
the current time-zone (Denmark in my case).

I also need a function to do the opposite calculation.

I looked through LibXML but was unable to find such a function, but maby I missed something? I found some 
date functions in LibEXSLT but nothing that fits my needs...

Regards,
Erik F. Andersen