[Yaffs] What is the maximum YAFFS2 maximum filesystem size

    I want to know clearly the maximam file system size for YAFFS2 can
handle.
    In file ysffs_guts.h, there're ysffs_Tags structure:
   typedef struct {
    unsigned chunkId:20;
    unsigned serialNumber:2;
    unsigned byteCount:10;
    unsigned objectId:18;
    unsigned ecc:12;
    unsigned unusedStuff:2;

} yaffs_Tags;
     I can calculate the maximum file system size YAFFS2 can handle by
following algorithm:
    (2^20)*(2^18)*(2kb)= 2^49B     //Chunk size is 2kb
    Am I right?
    Appreciate for your reply!  Thanks.