Внешние таблицы - только char?

CREATE TABLE ZASOS EXTERNAL 'E:\EXTFILES\ZASOS.DAT' (
    TOVID   INTEGER,
    OST     FLOAT,
    CENA    FLOAT,
    PRIH    FLOAT,
    REALIZ  FLOAT,
    DIF     INTEGER,
    NHD     INTEGER
);

type
  TOstRec = record
    tid: integer;
    ost, prih, realiz, cz : single;
    dif, nhd: integer;
  end;

var
  Tovars: array of TOstRec;

    f := FileCreate(ExtFile);
    for i := 0 to TovCount-1 do begin
        FileWrite(f, Tovars[i].tid, 4);
        FileWrite(f, Tovars[i].ost, 4);
        FileWrite(f, Tovars[i].cz, 4);
        FileWrite(f, Tovars[i].prih, 4);
        FileWrite(f, Tovars[i].realiz, 4);
        FileWrite(f, Tovars[i].dif, 4);
        FileWrite(f, Tovars[i].nhd, 4);
    end;
    FileClose(f);