[dxwg] [I18N] Various date types could be more specific (#957)

aphillips has just created a new issue for https://github.com/w3c/dxwg:

== [I18N] Various date types could be more specific ==
Property: release date
https://www.w3.org/TR/2019/WD-vocab-dcat-2-20190528/#Property:resource_release_date

A number of date values have range text like this:

>    rdfs:Literal encoded using the relevant ISO 8601 Date and Time compliant string [DATETIME] and typed using the appropriate XML Schema datatype [XMLSCHEMA11-2]

This is not very specific, since 8601 and schema provide a plethora of date/time types/value spaces. It might be better to be more specific and restrict this to RFC3339 full-date or date-time (i.e. in the case of a timestamp) or by specifying the XML Schema types `date` or `dateTime` (which is the same thing as the RFC).

[This comment is part of the I18N horizontal review.]

Please view or discuss this issue at https://github.com/w3c/dxwg/issues/957 using your GitHub account