Relational expressions compare two arithmetic expressions.
The allowed standard relational operators are :
The result of a relational expression is the value 0 for FALSE or -1 for TRUE.
For example, to select all the records where the difference between the values of the two fields MAGB and MAGV is less then 2.5 you can use one of the two equivalent expressions:
(MAGB - MAGV) .LT. 2.5 or (MAGB - MAGV) < 2.5