new ezcInputFormDefinitionElement( ezcInputFormDefinitionElement::OPTIONAL, 'float' ) );
    $form = new ezcInputForm( INPUT_POST, $def );

    echo "Valid properties:\n";
    var_dump( $form->getValidProperties() );

    echo "Invalid properties:\n";
    var_dump( $form->getInvalidProperties() );

    echo "Required properties:\n";
    var_dump( $form->getRequiredProperties() );

    echo "Optional properties:\n";
    var_dump( $form->getOptionalProperties() );
?>