Use XML attributes to represent datetimes and not RFC3339.
We want to be able to process feeds using XSLT and other basic XML processing tools. RFC3339 format means that they now ALSO need a RFC3339 parser to do anything interesting with dates. XML is a system for representing data structures. Lets use it to represent datetime data structures.
"Date Constructs" are actually DateTime Constructs and the naming should reflect that.
Replace Section 3.3 with:
3.3 DateTime Constructs
A DateTime construct is an element that describes a particular moment in UTC time.
A DateTime construct is an element with the following attributes.
DateTime constructs MAY be extended by namespace-qualified element children and attributes.
3.3.1 "year" attribute
Full common era year represented as 1-4096. May be 1-4 digits.
3.3.2 "month" attribute
Month of year represented as 1-12. May be 1 or 2 digits.
3.3.3 "mday" attribute
Day of month represented as 1-31. May be 1 or 2 digits.
3.3.4 "hour" attribute
Hour of day represented as 0-24. May be 1 or 2 digits.
3.3.5 "minute" attribute
Minute of hour represented as 0-59. May be 1 or 2 digits.
3.3.6 "second" attribute
Second of minute represented as 0-60. May be 1 or 2 digits.
3.3.7 "fraction" attribute
Fraction of second represented as [0-9]+
Much simpler handling of timestamps for XML processing tools.
The time is always UTC. Localization should be handled at the presentation layer.
Not worrying about years past 4096.