[Yaffs] Yaffs Packed Tags and bad block markings

I am using yaffs2 and i am looking at the arrangement of the extended tags areas. My question is i have a Samsung chip which uses bad block markers at the 0 byte of the 64-byte spare area. But when i pass the extended tags parameter to my nand_write function, the bad block maker is overwritten with the tag information. I was wondering was their a way to change the arrangement of the bad block marker. Or should i handle this in the mtd-layer. I was wondering what the layout of the extended tag area supposed to be in the nand spare area.

Thanks,
Lance