edit_link
edit_link is fired when a link is edited. The ID of the link is passed.
This hook is an action which means that it primarily acts as an event trigger, instead of a content filter. This is a semantic difference, but it will help you to remember what this hook does if you use it like this: add_action('edit_link', 'your_function');
This hook was introduced in WordPress 2.0, and will not work in earlier versions.