WordPress MU

So the concept of the wp_sitecategories table is new to me.

Can somebody explain its usage?

I just tried creating a category the regular way in the WP admin area and sure enough the entry shows up in the wp_sitecategories table.

But when I delete the category, the category is not removed from the wp_sitecategories table.

Why?

because other people might want to use it

Thanks for the reply, Steve, but that didn't really explain anything to me.

If no other blogs are using that category, logically it should be removed right?