This is record TLongWordRec.

public TLongWordRec = packed record
  case Integer of
    0: (LongWordValue: LongWord;);
    1: (High: Word;
        Low: Word;);
    2: (Words: array[0..1] of Word);
        Bytes: array[0..3] of Byte););
  end;

ImagingUtility (at line 72)