d><p>The property of the feature to use for marker icon.
Can be a JS function which accepts a feature and returns an index of <code>markerIcons</code>.
In either case the result must be one of the indexes of markerIcons.</p></td>
    </tr>
    <tr>
      <th>markerOptions</th>
      <td><p>The options for markers
Can be a single marker using <code><a href='http://www.rdocumentation.org/packages/leaflet/topics/makeIcon'>makeIcon</a></code>
or a list of markers using <code><a href='http://www.rdocumentation.o