The Alteria

Summary
The Alteria is the Arvonian name for the place that holds all the different planes. Every different plane has their own notation, using the greek alphabet. These were named by the Valenmar. They are all also assigned a member of the Valenmar.

Arvine (And Affiliated)

 * Arvine/Xynrear (Lore) : ααβτ [Desdemona]
 * Arvine (D&D Main) : ααβδ [Desdemona]
 * Arvine (D&D Alteria) : ααβθ [Desdemona]
 * Arvine (D&D Misc) : ααβλ [Desdemona]
 * Arvine (D&D 7th Age) : ααβρ [Desdemona]
 * Arvine (Ramar) : ααγς [Desdemona]
 * Arvine (Wardric's Woeful What-Ifs) : αακδ [Desdemona]
 * Nolach : α
 * Nesemphit : β

Earth

 * Earth (Dave Legends) : δη [Malinta]
 * Earth (Mark Legends) : δμ [Malinta]
 * Earth (Ian Legends) : δρ [Malinta]
 * Earth (Reality) : γ [Fuscia]
 * Earth (Memoirs) : χυε [Fuscia]

Yggdrasil (The World Tree) : οθγα [Hypatian]

 * The Faewild : οθγα-β
 * The Prime Material : οθγα-α

Milas Cluster
The rest of the Milas Cluster are notated according to the main plane that it's based around. The Milas Cluster is the primary cluster of realms within those planes, as such, the notation is simple. Within these notations, X represents the notation of the primary plane. There are also realms that exist outside of the Milas Cluster, but are also not alternate versions of one another. Due to their associations with a respective plane, they also maintain the X notation.
 * Hell : X - α - α
 * The Faerland : X - α - β
 * The Void : X - α - γ
 * Halivarnis : X - α - δ
 * Mount Dusklight : X - α - ε
 * Fort Cilamun : X - α - ζ
 * Birchleaf Island : X - α - η
 * The Underloaf : X - α - θ
 * Earthsky : X - α - ι
 * Wolfblood Forest : X - α - κ
 * The Eyre : X - α - λ
 * Môlvôr : X-θδυ
 * The Null : X-ζκξ

Alternate Canon Theory
First told by Erebus at the end of the 10th Age, this theory states that every single thing exists somewhere in the Alteria. This means that every single story ever written, every single dream, does exist. This could lend its hand to the general concept in several different stories. For example, here on earth, they are known as 'Parallel Universes'. In D&D, it is known as the 'multiverse'. And there are countless other examples around. For a full list of the different known canons, check the Alternate Canons page.