188.8.131.52. ByVal operator
This operator is a very special one. This actually does nothing but results the operand unaltered. Why to have such an operator? The reason is to help calling functions and passing arguments by value. When an expression is passed as an actual value for a function argument it is passed by value. In other words the function gets the value of the expression. When a variable is used as the actual argument for the function the function gets the variable and not the value. Of course the function can use the value of the variable, but when it alters the variable, the original variable is also changed. To avoid this you can use the operator ByVal in front of the variable, which is passed to a function as argument. In this case the argument is not a variable anymore, but rather an expression and thus the called function or subroutine can not alter the value of the argument variable.