Section 8,5: Expressions

 An expression represents a single value.  An expression can consist
 of a single constant, variable, record element, array element, or
 function reference; or combinations of these data items plus
 certain other elements, called operators.  Operators specify
 computations to be performed on the values of the data items and a
 single result is obtained.

 Expressions are classified as arithmetic, character, relational, or
 logical.  Arithmetic expressions produce numeric values; character
 expressions produce character values; and relational and logical
 expressions produce logical values.

 The data components of an expression must be compatible and must be
 joined by compatible operators.  Expressions are evaluated one
 operator at a time according to the rules of precedence.  The
 ranking assigned to each data type is as follows:

   Data Type                    Ranking
   ---------                    -------
   BYTE                          1 (lowest)
   LOGICAL*1                     1
   LOGICAL*2                     2
   LOGICAL*4                     3
   LOGICAL*8 (AXP only)          4
   INTEGER*1                     5
   INTEGER*2                     6
   INTEGER*4                     7
   INTEGER*8 (AXP only)          8
   REAL (REAL*4)                 9
   DOUBLE PRECISION (REAL*8)    10
   COMPLEX (COMPLEX*8)          11
   DOUBLE COMPLEX (COMPLEX*16)  12 (highest)

Sub-Topics

1. Arithmetic
2. Character
3. Logical
4. Relational