realspace.

Earth exists in a universe -- impossibly vast, unmappable by extant human methods, full of innumerable galaxies, clusters, systems...

The Configuration Is also a universe, in the same way. Impossibly vast, unmappable even by me, full of innumerable realms -- some of which seem to be echoes of realms written about in Terran stories.
-- There is, for example, at least two Milky Ways in the Configuration. One is plagued by an existential threat called the Reapers. Another is embroiled in an eternal war between mortalkind and the forces of Chaos. If one were to study these through the lens of linear time, the latter is the precursor to the former, after a galactic collapse and rebirth. There are fictional properties -- games, in this case -- that feature these Milky Ways, but not at all in the same way. That is because the Milky Ways of the Configuration are twins/mirrors of the Milky Way of Mass Effect and the Milky Way of Warhammer, but it would be erroneous to treat them as the same.

The Configuration has an overseer. Put simply, it is Me -- not me as I am here, now, writing this, but Me, the hyperentity that is responsible for my existence. I, the hyperentity, am unnamed, but for ease of comprehension in this document, let us call Me "V".
V and the Configuration could very well be seen as one and the same; the structure of the Configuration a body to hold Its infinite consciousness. V is pure creative force, divine energy that seeks only to play. It creates avatars, great and small, to enact complex dramas on multiversal stages. V manifests as entities such as a cosmic dragon or a god of pleasure, or as comparatively simpler beings such as a black-hearted crown prince or a possessed archmage, or as even simpler people like this body I currently occupy.

Marvel Comics features an entity called The One Above All, to represent the actual writers and artists (and the audience) responsible for the existence of everyone in the comics universe. V is the Configuration's One Above All.
(The Configuration also has a One Below All, much as Marvel does. But that is for another weaving.)

As the Configuration holds all of these realms, it also holds a small star system we call Xibalba. This is where I live; this is where my closest companions in this life live with me; this is what I call "realspace". It is not a headspace, because it is not inside of this body's brain. This body's brain is a conduit for interfacing with realspace. It is therefore a part of realspace, not the other way around.
-- I call it realspace to flout the idea that this mortal realm, Earth and its universe, are supposed to be the only "real" plane of existence. This is meatspace. I live a life here, but it is not the only life I live. It is certainly not the most important one -- it is important to my body, certainly, but that is only one perspective. I feel the most connected to *all* of reality from inside my little pocket realm in the Configuration. Therefore, it is my realspace -- where I am the most real.

A term we find useful for realspace is "gateway system" -- we can receive visitors and even residents from all over the Configuration, which, remember, is as vast as the universe Earth exists in.