Sector

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A sector is a distinct section in the same layer of headspace, akin to a separate region in a country. There are no or very few travel or communication difficulties from a sector to the rest of the layer/headspace. Sectors are characterized by their differences from the rest of the layer/headspace in areas like temperature, day/night cycle, and flow of time.

A system does not have to be layered to have sectors.

Related Terms
If a layer/headspace has a sector with different flow of time than other areas, it could be considered vartemporal.