Roger, you can also use pop-up boxes. Here is how to do it, all nicely colour coded so that even . . . well, you know.
[acronym="This is the pop-up message."]posted message[/acronym]For example, if you post:
There is a pop-up box hidden in this [acronym="This is the pop-up message."]posted message[/acronym] for you to find.you will get:
There is a pop-up box hidden in this posted message for you to find.