[Yaffs] ECC handling in YAFFS2

hello sir,
I didn't see the ECC been used for the large page read and write in YAFFS2.
If we see the spare area assignment standard for the large page, there are
12 bytes of ECC in the spare area.
But if we compare it extended Tag structure used in YAFFS2 its not matching.
Can you please help me out in handling ECC for large page(2k)in YAFFS2.

Regards,
srikanth.