Operands in an expression are connected by operators.  If there is more
  than one operator in an expression, the  operator  having  the  highest
  precedence is evaluated first. If an expression contains operators that
  have the same order of precedence, the operations  are  performed  from
  left to  right.  Use  parentheses  to  override  the  normal  order  of
  precedence.

      Operator  Precedence  Description

         +         7        Indicates a positive number
         -         7        Indicates a negative number
         *         6        Multiplies two numbers
         /         6        Divides two numbers
         +         5        Adds two numbers or concatenates two character
                            strings
         -         5        Subtracts two numbers or reduces a string
        .EQS.      4        Tests if two character strings are equal
        .GES.      4        Tests if first string is greater than or equal
                            to second
        .GTS.      4        Tests if first string is greater than second
        .LES.      4        Tests if first string is less than or equal to
                            second
        .LTS.      4        Tests if first string is less than second
        .NES.      4        Tests if two strings are not equal
        .EQ.       4        Tests if two numbers are equal
        .GE.       4        Tests if first number is greater than or equal
                            to second
        .GT.       4        Tests if first number is greater than second
        .LE.       4        Tests if first number is less than or equal
                            to second
        .LT.       4        Tests if first number is less than second
        .NE.       4        Tests if two numbers are not equal
        .NOT.      3        Logically negates a number
        .AND.      2        Combines two numbers with a logical AND
        .OR.       1        Combines two numbers with a logical OR