in size accordingly. Both Appelcline and Curtis D. Carbonell, in his book the Dread Trident: Tabletop Role-Playing Games and the Modern Fantastic, highlighted that information on the planes and the shared cosmology was codified in the Manual of the Planes (1987) and Tales of the Outer Planes (1988). Carbonell wrote that project leader and designer Jeff Grubb detailed "the schematization of the planes' requisite five area: the Prime Material, the Ethereal, the Astral, the Inner, and the Outer planes. This basic structure is still used in 5e, with some changes that provide minor rearrangements and clarifications [...]. Grubb's approach demonstrated a need to codify, while still remaining flexible, that has remained as a primary aim of the latest edition". Carbonell also highlighted that the 1989 Spelljammer campaign setting added cosmology that "allowed travel between the different settings" such as Dragonlance, Greyhawk, and the Forgotten Realms. However, campaign settings such as Dark Sun and Ravenloft were inaccessible in this cosmology. Then in 1993, TSR wanted to do a series of books about the Outer Planes which Zeb Cook said led to the creation of the Planescape campaign setting released in 1994. This campaign setting provided a framework to create adventures across the planes with the city of Sigil acting as a hometown and starting point for players. Carbonell called this setting "the most complex example of the multiverse created during the varieties of 2e's AD&D settings" and wrote: "A more nuanced and sophisticated attempt at harmonization, Planescape provided an alternate way to travel between the planes than Spelljammer's science-fantasy-oriented approach". The 3rd edition Manual of the Planes (2001) detailed both the inner and outer planes. Kevin Kulp, for DMs Guild, wrote that "the authors used an approach that said 'here's how it's been done in the past, and here are other ways you can do it,' which allowed the book to avoid setting planar mechanics in stone. Instead it gave DMs a modular approach by presenting Options, a flexible strategy that pleased both 1e and Planescape fans. Vast amounts of new ideas and new locations were presented, dovetailing nicely with canon from earlier editions". The 4th edition shifted the locations of the various planes to fit the new World Axis cosmology and added the Parallel Planes of the Feywild and the Shadowfell to the game; many of the changes were detailed in that edition's Manual of the Planes (2008). However, the