add_btn

Placeholder for the “add” button inside add
see add 
<table do='pages'>
  <tr do='each'><td do='[name]'/><td do='{summary}'/></tr>
  <tr do='form'><td colspan='2'><form>...</form></td></tr>
  <tr do='add'><td colspan='2'><r:add_btn/></td></tr>
</table>

We need this extra tag because we have to insert the link inside a <td>. It is not valid xhtml to put anchors inside <tr>.