<!doctype html>
<title>Option labels</title>
<select size=12>
  <option><!-- No children, no label-->
  <option><!-- No children, empty label-->
  <option>label<!-- No children, label-->
  <option><!-- No children, namespaced label-->

  <option>child<!-- Single child, no label-->
  <option>child<!-- Single child, empty label-->
  <option>label<!-- Single child, label-->
  <option>child<!-- Single child, namespaced label-->

  <option>child node<!-- Two children, no label-->
  <option>child node<!-- Two children, empty label-->
  <option>label<!-- Two children, label-->
  <option>child node<!-- Two children, namespaced label-->
</select>