[Yaffs] [Yaffs2]Tnode tallness and the maximum chunk id

Hi,
The YAFFS_TNODES_MAX_LEVEL is 6, so I think the maximum chunk id occupies
3*6+4=22 bits, which evaluates 0x003fffff. But YAFFS_MAX_CHUNK_ID is defined
as 0x000fffff, why?

I guess maybe it gets a little mess with chunk group size which is
usually 2^2.
Or do I mistake anything?

best wishes, shizheng