The 'error_recovery' specifies the action  to  be  taken  if  an
  error occurs during execution of the routine.  By default, after
  the first error, the error message is printed and  execution  is
  stopped.

  Execution of the CLOSE procedure causes the system to close  the
  file  and,  if the file is internal, to delete it.  Each file is
  automatically closed when control passes from the block in which
  it is declared.

  You cannot close  a  file  that  has  not  been  opened  (either
  explicitly  by  the OPEN procedure, or implicitly by the EXTEND,
  RESET, or REWRITE procedure).  If you attempt to  close  a  file
  that was never opened, an error occurs.

  The  file  can  be  in  any  mode  (inspection,  generation,  or
  undefined)  before  the CLOSE procedure is called.  Execution of
  CLOSE sets the mode to undefined.