The DWORD_DWORD structure defines a 64-bit integer value. This is used in DHCP_OPTION_DATA_ELEMENT (section 2.2.1.2.23).

 typedef struct _DWORD_DWORD {
   DWORD DWord1;
   DWORD DWord2;
 } DWORD_DWORD,
  *LPDWORD_DWORD;

DWord1: This is of type DWORD, specifying the upper 32 bits of the value.

DWord2: This is of type DWORD, specifying the lower 32 bits of the value.