The GuidArray structure is defined as follows.

 typedef struct _GuidArray {
   [range(0, MAX_RPC_GUID_ARRAY_COUNT)] 
     DWORD count;
   [size_is(count)] GUID* ptr;
 } GuidArray;

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

ptr: A pointer to an array of GUIDs.