If you are feeling adventurous have a play with this unknown entity. It's index is on get_maxplayers() + 1.
I spoke to Alfred from Valve some time back since I noticed this entity he said it was something to do with a timer as far as he knew.
No I didn't contact him specifically about this entity, it was about the player slot problem upon initial server startup. Last player index isn't loaded until server reaches maximum capacity, this bug is still not fixed either! Along with various other HLDS VGUI console bugs I reported as well
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