$alias fdopen='fdopen'(%val,%ref)      include 'phigs.f1.h'			! get the HP-PHIGS aliases      program Error				! program "Error.f"       include 'phigs.f2.h'			! get the HP-PHIGS constants      integer*4	WorkstnID			! workstation identifier      parameter (WorkstnID=1)			! value chosen by the user      integer*4	ConnID				! connection identifier      integer*4	WorkstnType			! workstation type      parameter (WorkstnType=POIDDX)		! outin, direct, dbl bfr, X      integer*4	ErrorRtn			! error-return variable      integer*4	OldHandler			! storage for addresses      external MyErrorHandler			! forward reference      integer*4 fdopen				! to get file descriptor      call popph(fdopen(fnum(7), 'w'//char(0)), 0)	! open phigs      call pue004('/dev/screen/phigs_window', ConnID)	! get connection ID      call popwk(WorkstnID, ConnID, WorkstnType)! open workstation      !--- make an error with the standard error-handler in effect -----------      print *, "--- Default error-handler in effect ------------------"      call pswkw(WorkstnID, 0.0, 0.0, 0.0, 0.0)	! set workstation window      !--- turn off error handling completely --------------------------------      print *, "--- No error-handler in effect -----------------------"      call pserhm(POFF)				! set error-handling mode: off      call pswkw(WorkstnID, 0.0, 0.0, 0.0, 0.0)	! set workstation window      !--- install custom error-handler and make error again -----------------      print *, "--- Custom error-handler in effect -------------------"      call pserhm(PON)				! set error-handling mode: on      call pue700(MyErrorHandler, ErrorRtn, OldHandler) ! replace error handler      if (ErrorRtn .ne. 0) then          print *, "Error", ErrorRtn, "from pue700; terminating."          stop      end if      call pswkw(WorkstnID, 0.0, 0.0, 0.0, 0.0)	! set workstation window      call pclwk(WorkstnID)			! close workstation      call pclph				! close phigs      stop					! stop processing      end					! end of program!***********************************************************************+*****      subroutine MyErrorHandler(ErrorNo, FuncID, ErrorFile)      integer*4	ErrorNo				! which error happened?      integer*4	FuncID				! which routine had the error?      integer*4	ErrorFile			! print error messages where?      print *,"MyErrorHandler: Error", ErrorNo, " occurred in ",     +  "routine", FuncID      print *,"My own call to the ERROR LOGGING routine (perlog):"      call perlog(ErrorNo, FuncID, ErrorFile)      return      end