Historical Rules · 13 October 2023
Rule 303.4
Official source text from the 13 October 2023 Rules release
Some enchantments have the subtype “Aura.” An Aura enters the battlefield attached to an object or player. What an Aura can be attached to is defined by its enchant keyword ability (see rule 702.5, “Enchant”). Other effects can limit what a permanent can be enchanted by.