Hidden

See Text field for complete documentation.

PHP

$box = register_cuztom_meta_box( $id, $post_type, array(
		
    'fields' => array(
        
        array(
            'id'    => '_data_hidden',
            'type'  => 'hidden',
            'label' => 'Field Label',
            'default_value' => 'Some value'
        ),

        ...

    )

) );