Different thread title icons

[rootX]

http://www.physicsforums.com/Nexus/statusicon/thread_dot.gif

http://www.physicsforums.com/Nexus/statusicon/thread.gif

http://www.physicsforums.com/Nexus/statusicon/thread_hot.gif

What's the difference? How some threads are hot and some other have bombs? I thought mine threads or threads to which I reply get bomb sign.

[Kurdt]

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