Warped Bubble Wrap model: the center is the reality source.

Dimensions are divided into 4 types.

1. A shared dimension. A dimension which spills out into other dimensions. Various matter movement limitations might apply.
2. A fully open dimension. Matter can move in and out with no limitations.
3. A partially enclosed dimension. Matter can move in and out, however matter original to the dimension cannot leave, or original matter migration is greatly limited.
4. A fully enclosed dimension. No matter can go in or out.

Type 1 dimensions are common. Most of the time matter can move in and out with no limitations, but in some cases various matter limitations might apply. A typical scenario is a time shift, when a dimension is completely identical, but shifted into either past or future.

Dimensions which have no matter limitations and yet do not spill into other dimensions are classified as Type 2. These dimensions require the Normal Portal to be accessed.

Type 3 dimensions are either not common or more difficult to locate. They feature a one-way biased entrance, usually pointed inwards, so that entering the dimension is straightforward, while going back is difficult or impossible. The funnels of Type 3 dimensions also tend to have more extreme limitations aside from a one-way bias.

Type 4 dimensions cannot be studied directly, but they have been inferred from measuring interdimensional variance. They have also been probed via the Exotic Portal.

A large number of theories have been proposed over the years in order to explain why different dimension types exist. The main difficulty was to understand what defines a type, and if it is defined by the properties of the dimension or the funnels. Nothing about the dimensions themselves seemed to hint at their types, nor had the study of dimensional funnels yield any helpful results in that regard. The limitations of the Normal Portal made it impossible to measure anything beyond the properties of the dimensional funnels, making all other hypotheses mere speculation.

In reality the amount of overlapping dimensions is huge and the pattern has a phasing effect

It was with the invention of the Exotic Portal that for the first time it became possible to measure interdimensional variance, and thus create a testable model of how different dimensions relate to each other.

It is now proposed that dimensions exist in a special type of 3D+ space where they are positioned around a common reality source. Dimension type is dependent not on the properties of dimensions themselves or the funnels, but rather by how far the dimension is away from our own dimension, as well as what its angle variance is. This model is colloquially known as the Warped Bubble Wrap model, although its academic title is Interdimensional Shifting, referring to the variance of dimensional coordinates in relation to the reality source.

Reality source was developed by Patrice Eastaughffe in the early 1920s through her experiments with the Normal Portal, although at the time the WBW model was not even conceived, and she developed it in order to be able to accurately map dimensions onto the Normal Portal's grid. This made it possible to save Portal states and go back to a dimension. Previously, in order to re-visit the dimension it was customary to keep the connection locked for weeks, month or, in some cases, years.

Reality source is an abstraction, rather than an actual entity: it is a concept which makes categorizing and describing dimensions easier by defining a theoretical set of “original properties” which can express a group of dimensions in terms of their deviation form these properties.

Reality source is defined from a superposition of all observed dimensions (local group snapshot). One can think of it as a “perfect variant”. For instance, we can imagine an idea of a chair. But every chair in reality will have deviations from the idea: the surface will not be perfectly smooth, the legs will not be perfectly parallel, etc. And if we carefully define the perfect chair, all other chairs can be defined by noting how they differ from this ideal.

Same is done with the reality source, only dimensions have much less basic properties that we are interested in, which makes defining a reality source a very useful way of describing each and every dimension in the local group.

By moving away from our reality source, the Exotic Portal can locate other dimension groups, which are “far away” from us and have to be described using other reality sources, although the distance between groups is mathematical, not spacial. Spatially, all the dimensions exist in exactly the same coordinates.