Greetings, oXygen list, One of my students (copied here) has discovered an interesting discrepancy between the way oXygen and the w3c Validator respond to the datetime attribute in XHTML. In oXygen, with an XHTML 5 file, the encoding of the datetime attribute with simply a year <time datetime="2019">2019</time> raises an error. The error notification disappears if we use an ISO formatted year-month or year-month-day datatype (as in <time datetime="2019-04">2019</time> or <time datetime="2019-04-15">2019</time>). The xsd:gYear datatype isn't recognized as valid in oXygen's validation of XHTML, but we notice that it's not flagged as an error by the w3c markup Validation service for an XHTML document. When we change the context from XHTML 5 to HTML in oXygen, the use of a year only in the @datetime attribute is valid and all is well. My student and I would like to know if there's a reason for the year being insufficient for @datetime in XHTML validation in oXygen, or if this is something perhaps to be corrected in oXygen's validation? Thanks! Elisa -- Elisa Beshero-Bondar, PhD Program Chair of Digital Media, Arts, and Technology | Professor of Digital Humanities | Director of the Digital Humanities Lab at Penn State Erie, The Behrend College Development site: https://newtfire.org