Date/time/date-time terminology cleanup in the Manual, JavaDocs and error messages. Various smaller additions about using "xs" and such. Note that ..._format value "xs" doesn't work yet, but it's already documented.
Generalized date/time/dateTime formatting mechanism so that it's possible to use "xs" as date/time/datetime_format setting value, and in general anything that you can use with ?string.<format> or ?string(<format>).