  C++ declaration of system services or RTL calls? 
 The Question is:
 
I recently installed the C++ v6.2 compiler (and also the CXXAE02062 patch). I
 have code that uses LIB$ESTABLISH defined as the following construct:
 extern "C"
 
  void         (*Lib$Establish (void(*)(void))) (void);
 
 
Compilation works just fine. Links create the following strange message.
%LINK-W-NUDFSYMS, 1 undefined symbol:
%LINK-I-UDFSYM,         void (*Lib$Establish(void (*)()))()
%LINK-W-USEUNDEF, undefined symbol void (*Lib$Establish(void(*)()))()
referenced
 
 
Code compiles fine on v5.6-014 (c++ v5.6c) on OpenVMS v6.2-1H3.
 
 
 The Answer is:
 
  Please use appropriate symbol casing for declarations as appropriate,
  as both C++ and the OpenVMS LINKER can use mixed-case externals.
 
  In this case, OpenVMS system services and run-time library (RTL) calls
  will typically use (and permit) either all-uppercase or all-lowercase
  symbols in the declarations.
 
  For details, and for an existing declaration of the lib$establish RTL
  call, please see the include module lib$routines.h.
 
  Also note that the lib$establish call is a special case among OpenVMS
  Alpha RTL calls, as this call and the associated signal handling
  mechanisms are implemented with the direct assistance of the compiler
  on OpenVMS Alpha systems.  (OpenVMS VAX uses a rather different
  implementation of signaling and condition handling.)  Please see the
  OpenVMS Programming Concepts manual and the C and C++ programming
  documentation for details on signals and signal handling.
 
 
