Subscription Icons

Okay, in the subscriptions there are two possible icons:

http://www.linuxforums.org/forum/lin...thread_dot.gif

AND

http://www.linuxforums.org/forum/lin...ad_dot_hot.gif

Whats the difference, one's red and one is blue....


EDIT::

And now I see:

http://www.linuxforums.org/forum/lin...ad_dot_new.gif

red one means that thread is hot (lot of people checked it)
yellow one means "new post"
blue one means that post is older (marked as read)

So yellow means new person, then I can use that to check, I just look for the last posters name, and if its mine then there's no one replied, but if sum1 eldes name is there, then there is a new reply, and red/hot topic, means there were lots of views?? And Blue is just other/normal/etc...