Input:

    <em>Emphasis</em>

Result:

Input:

    <img src="http://jigsaw.w3.org/css-validator/images/vcss"/>

Result on span:

Result alone:

Without closing:

The following is invalid HTML, and will generate an error:

    HTML parse error:
    <table>
    <td markdown="1">This is *true* markdown text. (no par)</td>
    <td markdown="block">This is *true* markdown text. (par)</td>
    </tr>

    HTML parse error:
    </table>