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The debugger supports most FORTRAN 77 operators and includes an additional
set of operators for convenience.  The additional operators are patterned
after those available in the C programming language.

The grammar that the debugger supports is close to that of the FORTRAN 77
language but there are a few instances where space characters must be used
to clear up any ambiguities.  For example, the expression


     1.eq.x

will result in an error since the debugger will form a floating-point
constant from the "1." leaving the string "eq.x".  If we introduce a space
character after the "1" then we clear up the ambiguity.


     1 .eq.x

Unlike FORTRAN, the parser in the debugger treats spaces as significant
characters.  Thus spaces must not be introduced in the middle of symbol
names, constants, multi-character operators like .EQ.  or //, etc.

Operators are presented in order of precedence, from lowest to highest.
 Operators on the same line have the same priority.


                                             Lowest Priority
     Assignment Operators
         =  +=  -=  *=  /=  %=  &=  |=  =  <<=  >>=
     Logical Operators
         .EQV.  .NEQV.
         .OR.
         .AND.
         .NOT.
     Bit Operators
         |
         
         &
     Relational Operators
         .EQ.  .NE.  .LT.  .LE.  .GT.  .GE.
     Shift and Concatenation Operators
         <<  >>  //
     Arithmetic Operators
         +  -
         *  /  %
         ** (unsupported)
     Unary Operators
         +  -
         ~  ++  --  &   *   %
         [type_name] unary_expr
         ?
     Binary Address Operator
         :
                                             Highest Priority

Parentheses can be used to order the evaluation of an expression.

In addition to the operators listed above, a number of primary expression
operators are supported.  These operators are used in identifying the object
to be operated upon.

()
    subscripting, substringing, or function call

.
    field selection

->
    field selection using a pointer

The following built-in functions may be used to convert the specified
argument to a particular type.


     INT( )      conversion to integer
     REAL( )     conversion to real
     DBLE( )     conversion to double-precision
     CMPLX( )    conversion to complex
     DCMPLX( )   conversion to double-precision complex

The following sections describe the operators presented above.