What does "any " in invo private tab means?

private $_tabs = array(
        'Invoices' => array(
            'controller' => 'invoices',
            'action' => 'index',
            'any' => false
        ),
        'Companies' => array(
            'controller' => 'companies',
            'action' => 'index',
            'any' => true
        ),
        'Products' => array(
            'controller' => 'products',
            'action' => 'index',
            'any' => true
        ),
        'Product Types' => array(
            'controller' => 'producttypes',
            'action' => 'index',
            'any' => true

what does "any " mean here??? i am new to phalcon