message <span class="message">CreateInstallerArg</span>
{
  <span class="comment">/** 
   * If specified makes the installer perform an upgrade instead of a new
   * installation. An upgrade causes the widget on the host to use the
   * new widget file once installed.
   */</span>
  optional <span class="string">string     </span> widgetID   = 1; 
  <span class="comment">/** 
   * Which type the installer should be created for.
   * The default is to create it for a widget installation.
   */</span>
  optional <span class="number">Widget.Type</span> widgetType = 2; 
}
