An extradimensional space is a volume that does not interact with other things, except at any entry points; it is a space that does not exist in the normal coordinates of the world outside itself. When an extradimensional space is dispelled, all creatures and objects are transported out the nearest entry point, to the closest open region.
Entry points are flat regions that serve as a border between an extradimensional space and some other space. Creatures, objects, light, and so on can pass through the entry points into or out of the extradimensional space without necessarily even noticing that they have done so, even if one portal is in a completely different place from the other, like one on the ground while the other is inside a zeppelin.
The walls of an extradimensional space are indestructible, solid, completely immutable, and high in friction. They glow a gentle purple.
The gravity of an extradimensional space is equal to the average gravity of all entry points.
When created, an extradimensional space is filled with a standard pressure's worth of breathable air.
- 1000 meters above sea level, it creates light wind in a blast outwards for a distance equal to twice the longest dimension of the entry point for a number of rounds equal to its Volume Ratio.
- 10000 meters above sea level, it creates strong wind in a blast outwards for a distance equal to twice the longest dimension of the entry point for a number of rounds equal to half its Volume Ratio, and light wind in a blast outwards twice that distance. For a number of rounds after that equal to its Volume Ratio, it creates light wind as though it were 1000 meters above sea level.
- At 1.25 atmospheres (3 meters underwater, for example), it functions as 1000 meters above sea level, but the wind blows inwards.
- At 2 atmospheres (10 meters underwater, for example), it functions as 10000 meters above sea level, but the wind blows inwards.
If the difference in pressure is large enough to cause any wind, the opening of the extradimensional space creates a loud pop, audible from 500 meters away.
The shortest distance between two points can sometimes be significantly altered by the presence of an extradimensional space. Calculating distances depends on the purpose it is used for:
Other effects that don't care about fitting through entry points, like distance limits for spells, may not use a path which reenters reality or a given extradimensional space after leaving it.