There is no top-level element for dates; however, the date type deserves its own section because almost every top-level element specifies dates, and HR-XSL always formats them the same way.
HR-XSL supports the following date elements:
StringDate. Formatted as-is.
YearMonth.
The YYYY-MM pattern is converted to month yearmonthmonth.format is equal to long, full month names are used. Otherwise, abbreviated month names are used.
AnyDate.
If the value matches the pattern YYYY-MM-DD, it is formatted like the YearMonth type, except that the value for DD is inserted. (For example, 2003-10-23 becomes Oct. 23, 2003.) HR-XSL also recognizes the pre-defined values notApplicable and notKnown and localizes them accordingly. Otherwise, the value is formatted as-is.
The HR-XML website has more documentation.