This operator may be used as a binary operator in an expression like x⧢y. The user may install binary methods for handling such expressions with code such as
X ⧢ Y := (x,y) -> ...
where X is the class of x and Y is the class of y.
To insert this character in Emacs, you may press C-x 8 RET or M-x insert-char and then enter "shuffle product" in the minibuffer.
The source of this document is in Macaulay2Doc/operators/tensor.m2:47:0.