.

function Subst(Drive:char;Path:string):boolean;
var
  zPathName:array[0..80] of char;
  zDrvStr:array[0..5] of char;
  Flags:dWord;
begin
  Flags:=0;
  zDrvStr[0]:=Drive; zDrvStr[1]:=':'; zDrvStr[2]:=#0;
  if (Path='/d') or
     (Path='/D')
  then begin
    Flags:=DDD_REMOVE_DEFINITION or DDD_RAW_TARGET_PATH;
    QueryDOSDevice(zDrvStr,zPathName,sizeof(zPathName));
  end else begin
    if not(DirectoryExists(Path)) then begin
      Result:=false; exit;
    end;
    StrPCopy(zPathName,Path);
  end;
  Result:=DefineDOSDevice(Flags,zDrvStr,zPathName);
end; (* Subst *)