Create(AFileName,Mode,438);

https://gitlab.com/freepascal.org/fpc/source/-/blob/main/rtl/objpas/classes/streams.inc has code

constructor TFileStream.Create(const AFileName: string; Mode: Word);

begin
  Create(AFileName,Mode,438);
end;

can you please decipher int constant into sum of IDs? To increase maintainability of code.