Campo hidden em JSF

Alguém sabe para que serve o campo hidden incluído nos forms pelo JSF. Eu pensava que era utilizado quando a árvore de componentes era salva no cliente:

javax.faces.STATE_SAVING_METHOD client

mas mesmo quando salvo a árvore no cliente ele cria um novo campo hidden e mantém o outro aparentemente inutilizado:

<h3>Por favor entrar com nome e senha.</h3>
        <table>
           <tr>
              <td>Nome:</td>
              <td>
                 <input type="text" name="_id0:_id1" />
              </td>
           </tr>             
           <tr>
              <td>Senha:</td>
              <td>
                 <input type="password" name="_id0:_id2" value="" />
              </td>
           </tr>
        </table>
        <p>
           <input type="submit" name="_id0:_id3" value="Login" /> 
        </p>
      <input type="hidden" name="com.sun.faces.VIEW" value="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" />

Ainda não consegui entender para que serve:

Alguém pode me ajudar?

Topicos relacionados