typedef struct _CM_NAME_CONTROL_BLOCK
{
     UCHAR Compressed;
     WORD RefCount;
     union
     {
          CM_NAME_HASH NameHash;
          struct
          {
               ULONG ConvKey;
               PCM_KEY_HASH NextHash;
               WORD NameLength;
               WCHAR Name[1];
          };
     };
} CM_NAME_CONTROL_BLOCK, *PCM_NAME_CONTROL_BLOCK;

Windows Vista Kernel Structures