The computed code sets the variable X,
and makes use of the X(order#) array. In this case X(1) refers to the EMAIL
NAME, the cross-reference value we defined with order number 1, and X(2) refers
to EMAIL ADDRESS, the cross-reference value we defined with order number 2. Our
computed expression sets X to email_name@email_domain, and converts the result
to uppercase. This will be our third cross-reference value (order number 3),
which will be subscript 1 (the only data subscript) in our index.