GLOBAL variable-name [ , variable-name ... ]

   Synopsis:
      Declares global variables

   Notes:
      Global variables are available to the whole Axbasic script, whereas local
         variables (declared with a LOCAL statement) are only available within 
         the subroutine in which they are declared.
      Var-Names must be a scalar variable. Array variables can be declared as
         global within a DIM GLOBAL statement.

   Availability:
      GLOBAL is not available in scripts with primitive line numbers.

   Examples:
      GLOBAL string$, other$
      LET string$ = "Hello world!"
      LET other$ = "Goodbye cruel world!"

      CALL mysub ()
      END

      SUB STRING mysub ()
         ! string$ and other$ can still be used in this subroutine
         PRINT string$
         PRINT other$
      END SUB
