Patent ID: 7340663

Claim:
In a method of encoding multiword information, which includes the steps of encoding information into first code words of an error correcting code over a first Galois field, and arranging a number of the first code words in columns of a code block comprising a user data sub-block and a parity data sub-block, wherein said code block comprises the first code words over the first Galois field arranged in the columns of said code block, a method of embedding an additional layer of error correction into the error correcting code, said method comprising the steps of: adding bits of a predetermined number to the first code words to form second code words over a second Galois field arranged in the columns of said code block, wherein the bits have different bit values and comprise an identical sequence of bits added to each row; encoding rows of at least said user data sub-block separately or in groups using a horizontal error correcting code over the second Galois field larger than said first Galois field to obtain horizontal parities; and embedding said horizontal parities as the additional layer in said error correcting code.