The standard Upper case function is supported for converting all characters in an expression to upper case. It is valid only if the expression evaluates to a character data type. The SQL generated is UPPER (expression), and the type returned is that of the expression. When dragging an Upper operator into a variable, the following tree element is created
Columns and/or other expressions can be moved into the (empty) branches of the tree where the first argument is expression1 as indicated above, and the second expression2.
There are no special properties for the Upper operator.