binary mekso operator: Let the inputs X_{1} and X_{2} be sets in the same universal set O; then the result of this operator applied to them is X_{1^c
\cup X}, where for any A \subseteq O, A^{c }= O \setminus A.

Generalizes to n-ary, for any integer n>1 or n being an infinity. This operator generates all three of the basic set operators: union (jo'e), intersection (ku'a), and relative complement (kei'i). See also: xa'ei'u. .krtis. calls it the "union(-type) hash operator", but has never seen a generally used name for it.

- xa'ei'u
*(exp!)* - binary mekso operator: Let the inputs X
_{1}and X_{2}be sets in the same universal set O; then the result of this operator applied to them is X_{1^c \cap X}, where for any A \subseteq O, A^{c }= O \setminus A.