If the expression whose value must be of boolean data type is complex,
it can consist of some subexpressions (see above)
that are put together by logical conjunctions (AND, OR, NOT, .EQUAL TO, NOT EQUAL TO).
If you want to express priority in such an expression, you can use parentheses.
From the conjunctions mentioned below, you can choose either form
Every sign of the form
.operator. must be surrounded by a white space.
Logical EQUAL TO
Logical NOT EQUAL TO