meaning of "heat sig"

[KLPNO]

Hi everyone
I'd like to ask what 'heat sig' means in the following context:

(Soldiers walking down the corridor in the convention center looking for the prisoner who supposedly is being held in one of the meetings room).

He was about to conk the helmet on the side again, when he noticed something odd: a heat sig in the ceiling that wasn't where one of the lights was. It was just a small circle.
Like the muzzle of an energy weapon. Vega immediately fired at the sig.

[Yankee]

Hi KLPNO

I assume that is a shortened form of "heat signature" and that more or less means "source of heat". I believe infrared devices can detect sources of heat/heat signatures and make them "visible", for example.
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Amy
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ESL teacher, translator, and a native speaker of American English

[KLPNO]