delphi record中的case

  _SYSTEM_INFO = record
    case Integer of
      0: (
        dwOemId: DWORD);
      1: (
        wProcessorArchitecture: Word;
        wReserved: Word;
        dwPageSize: DWORD;
        lpMinimumApplicationAddress: Pointer;
        lpMaximumApplicationAddress: Pointer;
        dwActiveProcessorMask: DWORD_PTR;
        dwNumberOfProcessors: DWORD;
        dwProcessorType: DWORD;
        dwAllocationGranularity: DWORD;
        wProcessorLevel: Word;
        wProcessorRevision: Word);
  end;