What Does The @ Mean in Category Headings?

I thought I knew but I checked the Resource Zone for confirmation and could not find it.
So for example: "dream interpretation services@"
What does the@ indicate?
Thanks

That would be called an @link or a symlink. It is a category that could belong in two (or more) places. The category is developed in one location and links to the category are placed whereever the category might also be located.

http://dmoz.org/erz/glossary.html#@

Thanks so much : )