WordPress at a glance
action is not described

admin_print_styles action-hook . WP 2.6.0

Fires when styles are printed for all admin pages.

Usage

add_action( 'admin_print_styles', 'action_function_name_9161' );
function action_function_name_9161(){
	// action...
}

Where the hook is called

In file: /wp-admin/admin-header.php
admin_print_styles
wp-admin/admin-header.php 113
do_action( 'admin_print_styles' );
wp-includes/class-wp-customize-widgets.php 649
do_action( 'admin_print_styles' );
wp-admin/includes/media.php 518
do_action( 'admin_print_styles' );
wp-admin/includes/template.php 1931
do_action( 'admin_print_styles' );
woocommerce/includes/admin/class-wc-admin-setup-wizard.php 329
<?php do_action( 'admin_print_styles' ); ?>

Where the hook is used (in WP core)

wp-admin/includes/admin-filters.php 55
add_filter( 'admin_print_styles', 'wp_resource_hints', 1 );
wp-includes/default-filters.php 347
add_action( 'admin_print_styles', 'print_emoji_styles' );
wp-includes/default-filters.php 348
add_action( 'admin_print_styles', 'print_admin_styles', 20 );