8.3.2 The RexxRegisterFunctionExe() function

This function is used to register an external function handler
with the interface. The external function handler must be a
procedure located within the code of  the application. After
registration, the REXX interpreter can execute external functions
as if they were built-ins.

The prototype for RexxRegisterFunctionExe() is:

     APIRET APIENTRY RexxRegisterFunctionExe(
           PSZ FuncName,
           PFN EntryPoint
     ) ;

All the parameters are input, and their significance are:

     [FuncName]
          Points to an ASCII NUL terminated character string which
          defines the name of the external function to be
          registered. This is the same name as the REXX
          interpreter uses with a function call or via  the CALL
          command.
     [EntryPoint]
          Points to the entrypoint of the external function
          handler routine for the function to be registered. See
          the section on External Function  Handlers for more
          information.

The area pointed to by  FuncName is copied to a private area in
the interface, so the programmer may de-allocate or reuse the area
used for this parameter after the call has returned.

The RexxRegisterFunctionExe() returns an unsigned long, which
carries status information describing the outcome of the
operation. The status will be one of the RXFUNC values:

     [ RXFUNC_OK]
          The handler was successfully registered.
     [RXFUNC_DUP]
          The  handler was successfully registered. There already
          existed another external function handler which was
          registered with RexxRegisterFunctionExe(), but this will
          be shadowed by the newly registered handler.
     [RXFUNC_NOEMEM]
          The handler was not registered, due to lack of memory.


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