void save(Archive & ar,
const posix_time::ptime& pt,
unsigned int /*version*/)
{
// from_iso_string does not include fractional seconds
// therefore date and time_duration are used
typename posix_time::ptime::date_type d = pt.date();
ar & make_nvp("ptime_date", d);
if(!pt.is_special()) {
typename posix_time::ptime::time_duration_type td = pt.time_of_day();
ar & make_nvp("ptime_time_duration", td);
}
}
