Remove column separators in a table header

Remove column separators in the header row of a table.

Let’s say that you want to format a table so that, while it has vertical and horizontal rules in the body, it doesn’t have vertical rules in the header row, like this:
../_images/table_heading_no_colsep.png

The most DITA-compliant approach is simply to set colsep="0" on each of the <entry> elements in the table’s <thead> element:

<thead>
   <row>
      <entry colsep="0">State</entry>
      <entry colsep="0">Capital</entry>
      <entry colsep="0">Population</entry>
   </row>
</thead>

However, maybe this design decision is recent and needs to be applied retroactively to hundreds of tables. You could ...