The 'history' is a value that indicates whether the file  exists
  or  if  VSI Pascal must create the file.  If you specify OLD and
  if VSI Pascal cannot find the file, an  error  occurs.   If  you
  specify  READONLY,  you  can  only  read  from  the file; if you
  attempt to write to the file, an error occurs.  If  you  specify
  UNKNOWN, VSI Pascal looks for an existing file but creates a new
  file if there is no  existing  file.   If  you  specify  OLD  or
  UNKNOWN  and  if  the  attempt to open the file generates a file
  protection error, VSI Pascal tries again using READONLY.

  NEW is the default for OPEN/REWRITE openings, while OLD  is  the
  default for EXTEND/RESET openings.