IsXsDateTimeStampUtc🔗
          Check that 
        text is a xs:dateTimeStamp with time zone set to UTC.
        
            The text is assumed to match a pre-defined pattern for xs:dateTimeStamp with
            the time zone set to UTC. In this function, we check for days of month (e.g.,
            February 29th).
          
Code
Code not available as this is implementation-specific.