The UPDATE procedure writes the contents of the file buffer into
  the current component.

  Syntax:

     UPDATE( file_variable[[, ERROR := error-recovery]] );

  The 'file_variable' is the name of the file variable  associated
  with the file whose component is to be updated.

  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.

  The file must be in inspection mode before UPDATE is called;  it
  remains in that mode after the procedure's execution.

  The UPDATE procedure is legal for files that  have  been  opened
  for  random access ("direct" or "keyed").  The current component
  must already have been locked by a successful FIND, FINDK,  GET,
  RESET,  or  RESETK  procedure  before  the  contents of the file
  buffer can be rewritten into it.  After  the  update  has  taken
  place, the component is unlocked and UFB returns TRUE.

  See the "HP  Pascal  Language  Reference  Manual"  for  complete
  information on the UPDATE procedure.