This option, along with DESCENDING, allows you  to  specify  the
  collating  sequence  for the key field.  By default, the primary
  key and alternate key are ASCENDING.

  When creating a new file, Pascal will create the  key  with  the
  collating  order  specified.  When opening an existing file, the
  Run-Time Library will verify that the existing key  matches  the
  collating  order  specified.  If neither ASCENDING or DESCENDING
  is specified when opening an existing file, both types  will  be
  accepted.