The planes of the Forgotten Realms were retooled in the 4th Edition to match the new default cosmology, with many of the planes or realms being relocated to the Astral Sea, and a handful now located in the Elemental Chaos. Appelcline highlighted that the 4th Edition World Axis model "had actually originated with the Forgotten Realms, which was planning a view of the heavens as early as 2005 or 2006. It was then co-opted by the SCRAMJET world design team for D&D 4e". Fictional planar travel Portals, conduits and gates are all openings leading from one location to another; some lead to locations in the same plane, others to different planes entirely. Although the three terms are often used interchangeably, there are notable distinctions: Portals are bounded by pre-existing openings (usually doors and arches); the portal is destroyed when the opening is. Portals also require portal keys to open; a key is usually a physical object, but it can also be an action or a state of being. Naturally occurring portals will often appear at random (a common occurrence in the city of Sigil, "City of Doors", in the Planescape campaign setting); some portals only exist for a brief period of time, or shift from one location to another. Conduits are also naturally occurring, but they are natural phenomena, the planar equivalent of whirlpools and tornadoes. Conduits are only known to occur in the Astral and Ethereal Planes. A type of conduit known as a color pool is a common gateway from the Astral Plane to the Outer Planes. A vortex is a link from a Prime Material world to the Inner Planes, which begin in areas of intense concentration of some element (e.g., the heart of a volcano might be a vortex to the Plane of Fire). There also used to be living vortices which the sorcerer-monarchs of Athas have managed to maintain, like syphoning water through a hose, and use to empower their "priests," the Templars. Gates are portals that are not bounded by physical apertures; gates are rare, and usually appear as a result of magical spells and rare planar phenomena. Lastly, planar bleeding occurs when regions of two planes coexist; such phenomena are usually short-lived, and disastrous for their environments. Planar pathways Planar pathways are special landscape features appearing in multiple planes or layers of a plane. Travel along a planar pathway results in travel along