The UInt64Array structure is defined as follows.

 typedef struct _UInt64Array {
   [range(0, MAX_RPC_UINT64_ARRAY_COUNT)] 
     DWORD count;
   [size_is(count)] DWORD64* ptr;
 } UInt64Array;

count: A 32-bit unsigned integer that contains the number of 64-bit integers pointed to by ptr.

ptr: A pointer to an array of unsigned 64-bit integers.