15.4.5.1 Fortran Operators and Expressions
Operators must be defined on values of specific types.  For instance,
+ is defined on numbers, but not on characters or other non-
arithmetic types.  Operators are often defined on groups of types.
     
- **
- The exponentiation operator.  It raises the first operand to the power
of the second one.
     
 
- :
- The range operator.  Normally used in the form of array(low:high) to
represent a section of array.
     
 
- %
- The access component operator.  Normally used to access elements in derived
types.  Also suitable for unions.  As unions aren't part of regular Fortran,
this can only happen when accessing a register that uses a gdbarch-defined
union type.