Table with header cells in the top row only

For this type of table, you have to embed the table rows in the <thead> element.

Table 1. Example: Oxygen Events
Event	Date	Location
Evolution of TC 2018	May 31 - June 1, 2018	Sofia, Bulgaria
Markup UK	June 9 - 10, 2018	London, United Kingdom
Balisage 2018 - The Markup Conference	July 31 - August 3, 2018	Rockville, Maryland, USA

<table>
  <title>
    <b>Oxygen Events</b>
  </title>
  <tgroup cols="3">
      <colspec colname="COLSPEC0" colwidth="1*"/>
      <colspec colname="COLSPEC1" colwidth="1.1*"/>
      <colspec colname="newCol3" colwidth="1*"/>
  <thead>
    <row>
      <entry colname="COLSPEC0" valign="top">Event</entry>
      <entry colname="COLSPEC1" valign="top">Date</entry>
      <entry>Location</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>Evolution of TC 2018</entry>
      <entry>May 31 - June 1, 2018</entry>
      <entry>Sofia, Bulgaria</entry>
    </row>
    <row>
      <entry>Markup UK</entry>
      <entry>June 9 - 10, 2018</entry>
      <entry>London, United Kingdom</entry>
    </row>
    <row>
      <entry>Balisage 2018 - The Markup Conference</entry>
      <entry>July 31 - August 3, 2018</entry>
      <entry>Rockville, Maryland, USA</entry>
    </row>
  </tbody>
  </tgroup>
</table>