Action Hook: Fires just before pinging back links found in a post.

Action Hook: Fires immediately after transitioning a comment’s status from one to another in the database and removing the comment from the object cache, but prior to all status transition hooks.

Filter Hook: Filters the user agent sent when pinging-back a URL.

Filter Hook: Filters the comment content before it is updated in the database.

Filter Hook: Filters the comment data immediately before it is updated in the database.

Filter Hook: Filters the comment author’s user ID before it is set.

Filter Hook: Filters the comment author’s browser user agent before it is set.