WordPress at a glance
action is not described

wp_default_styles action-hook . WP 2.6.0

Fires when the WP_Styles instance is initialized.

Usage

add_action( 'wp_default_styles', 'action_function_name_4236' );
function action_function_name_4236( $this ){
	// action...
}
$this(WP_Styles)
WP_Styles instance (passed by reference).

Where the hook is called

WP_Styles::__construct()
wp_default_styles
wp-includes/class.wp-styles.php 116
do_action_ref_array( 'wp_default_styles', array(&$this) );

Where the hook is used (in WP core)

wp-includes/default-filters.php 492
add_action( 'wp_default_styles', 'wp_default_styles' );