WordPress at a glance
action is not described

(old_status)_to_(new_status) action-hook . WP 2.3.0

Fires when a post is transitioned from one status to another.

The dynamic portions of the hook name, $new_status and $old status, refer to the old and new post statuses, respectively.

Usage

add_action( '(old_status)_to_(new_status)', 'action_function_name_5313' );
function action_function_name_5313( $post ){
	// action...
}
$post(WP_Post)
Post object.

Where the hook is called

wp_transition_post_status()
(old_status)_to_(new_status)
wp-includes/post.php 4214
do_action( "{$old_status}_to_{$new_status}", $post );

Where the hook is used (in WP core)

wp-includes/ms-default-filters.php 25
add_action( 'init', 'maybe_add_existing_user_to_blog' );
wp-includes/ms-default-filters.php 27
add_action( 'wpmu_activate_user', 'add_new_user_to_blog', 10, 3 );
wp-includes/default-filters.php 367
add_action( 'transition_post_status', '_wp_auto_add_pages_to_menu', 10, 3 );
wp-includes/default-filters.php 527
add_filter( 'image_send_to_editor', 'image_add_caption', 20, 8 );
wp-includes/default-filters.php 528
add_filter( 'media_send_to_editor', 'image_media_send_to_editor', 10, 3 );
wp-includes/class-wp-customize-manager.php 382
add_filter( 'heartbeat_settings', array( $this, 'add_customize_screen_to_heartbeat_settings' ) );
wp-admin/includes/ajax-actions.php 2681
remove_filter( 'media_send_to_editor', 'image_media_send_to_editor' );
wp-admin/includes/media.php 2040
add_filter('attachment_fields_to_edit', 'media_post_single_attachment_fields_to_edit', 10, 2);
wp-admin/includes/media.php 2256
<?php add_filter('attachment_fields_to_edit', 'media_post_single_attachment_fields_to_edit', 10, 2); ?>
wp-admin/includes/media.php 2524
<?php add_filter('attachment_fields_to_edit', 'media_post_single_attachment_fields_to_edit', 10, 2); ?>
wp-admin/includes/admin-filters.php 33
add_filter( 'attachment_fields_to_save', 'image_attachment_fields_to_save', 10, 2 );
wp-admin/includes/admin-filters.php 131
add_action( '_core_updated_successfully', '_redirect_to_about_wordpress' );
wp-admin/async-upload.php 61
add_filter('attachment_fields_to_edit', 'media_single_attachment_fields_to_edit', 10, 2);
wp-admin/async-upload.php 65
add_filter('attachment_fields_to_edit', 'media_post_single_attachment_fields_to_edit', 10, 2);
wp-admin/media.php 65
add_filter('attachment_fields_to_edit', 'media_single_attachment_fields_to_edit', 10, 2);