Historical Rules · 18 June 2010
Rule 309.3
Official source text from the 18 June 2010 Rules release
Plane subtypes are listed after a long dash, and may be multiple words: "Plane -- Serra's Realm." All words after the dash are, collectively, a single subtype. Planar subtypes are called planar types. A plane can have only one subtype. See rule 204.3m for the complete list of planar types.