WMF Header. Internal use.

TMetafileHeader = packed record
  Key: Longint;
  Handle: SmallInt;
  Rect: TSmallRect;
  Inch: Word;
  Reserved: Longint;
  CheckSum: Word;
end;

struct TMetafileHeader {
  Longint Key;
  SmallInt Handle;
  TSmallRect Rect;
  Word Inch;
  Longint Reserved;
  Word CheckSum;
};