The definition of "HTML element" . defines the whole document and has a start tag (< xtml >) and end tag (< /xtml >) defines the partial document and has a start tag (< html >) and end tag (< /html >) defines the whole document and has a start tag (< html >) and end tag (< /html >) defines the partial document and has a start tag (< xtml >) and end tag (< /xtml >)