WordPress at a glance
action is not described

pre_get_networks action-hook . WP 4.6.0

Fires before networks are retrieved.

Usage

add_action( 'pre_get_networks', 'action_function_name_5126' );
function action_function_name_5126( $this ){
	// action...
}
$this(WP_Network_Query)
Current instance of WP_Network_Query (passed by reference).

Where the hook is called

WP_Network_Query::get_networks()
pre_get_networks
wp-includes/class-wp-network-query.php 199
do_action_ref_array( 'pre_get_networks', array( &$this ) );

Where the hook is used (in WP core)

Does not used.