The UNLOCK procedure releases the  current  file  component  for
  access by other processes.

  Syntax:

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

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

  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 UNLOCK is called;  it
  remains in inspection mode after UNLOCK has executed.

  If the component at which the file  pointer  is  positioned  has
  been locked, the UNLOCK procedure releases it.