Thanks for the suggestion anyway. I found out it is possible to do if you could add the following to your html somehow
Back to: <a href="horizontal_rules.htm" title="Learn about horizontal rules">horizontal rules</a>
You get the effect by adding title="My message" to the link. This enables hyperlinks to have a similar description message to that which has long been available in images (through the ALT text). Use it when some explanation would help. If you are just repeating words in the text, then it is superfluous. It only works in the more modern browsers, but older browsers just ignore it, so it is safe to use.