title: wordpress - What are the valid values of 'std' for 'List Item' option tree type?
body: <p>I want to have a default value (<code>'std'</code>) for a <code>list-item</code> type. I know how to set <code>std</code> for types other than <code>list-item</code>. Here's an example:</p>
  
  <pre><code>array(
      'id'          =&gt; 'logo',
      'label'       =&gt; 'Logo',
      'std'         =&gt; OT_URL.'others/logo@2x.png', // This is std for upload type.
      'type'        =&gt; 'upload',
  ),
  array(
      'id'          =&gt; 'regions-page',
      'label'       =&gt; 'Default Page Widgets Area',
      'std'         =&gt; 'right', // This is std for radio-image type.
      'type'        =&gt; 'radio',
      'choices'     =&gt; array(
          array(
              'value'       =&gt; 'right',
              'label'       =&gt; 'Region 2',
          ),
          array(
              'value'       =&gt; 'left',
              'label'       =&gt; 'Region 3',
          ),
      )
  </code></pre>
  
  <p>For types like <code>radio</code> and <code>select</code> there are some <code>choices</code> which <code>std</code> may refer to one of their <code>value</code>s. <code>list-item</code> type has something like <code>choices</code> called <code>settings</code>. Here's an example of <code>list-item</code> type:</p>
  
  <pre><code>array(
      'id'          =&gt; 'home-ads-items',
      'label'       =&gt; 'Add ADS. banner under Featured Products',
      'std'         =&gt; '', // I want to set this in order to Image setting would be its default.
      'type'        =&gt; 'list-item',
      'settings'    =&gt; array(
          array(
              'id'      =&gt; 'img',
              'label'   =&gt; 'Image',
              'std'     =&gt; '',
              'type'    =&gt; 'upload',
              'class'   =&gt; '',
              'choices' =&gt; array()
          ),
          ...
  </code></pre>
  
  <p>I want to set <code>std</code> in order to have <code>Image</code> as default value. But I don't know how.</p>