Library /sys$common/syshlp/basichelp.hlb Run time errors, ILLRESSUB  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Illegal RESUME to subroutine (ERR=247)

  While in an error handler activated by an ON ERROR GO BACK, the  error
  handler  attempts  to  RESUME  without  a line number or a label.  You
  cannot RESUME to a line or label in any program module except the  one
  containing  the  error  handler.   This error cannot be trapped with a
  BASIC error handler.