U+29DF "⧟" Double-Ended Multimap Unicode Character

U+29DF "⧟" Double-Ended Multimap is a typographic symbol that represents a mathematical construct used in computer science and relational algebra, signifying a bidirectional mapping where each element in one set can be associated with multiple elements in another set, and vice versa. This character is encoded in the Miscellaneous Mathematical Symbols-B block and is visually depicted as a plus sign with two arrows pointing outward in opposite directions, one from each end. Its purpose is to provide a clear, compact notation for discussing and writing about functions or relations that are not one to one but allow for multiple correspondences on both sides.