An unencoded m -bit data input sequence is divided into a block of n bits and a block of m-n bits. The block of n bits is divided into a first set of n +1 encoded bits, wherein at least one of P 1subblocks of the first set satisfies a G , M and I constraints. The first set of n +1 encoded bits is mapped into a second set of n +1 encoded bits wherein at least one of P 2 subblocks of the second set gives rise to at least Q 1 transitions after 1/(1+ D 2 ) precoding. A second set of n +1 encoded bits is divided into P 3 encoded subblocks and the P 3 encoded subblocks are interleaved among ( m-n )/s unencoded symbols so as to form a ( m+ 1)-bit output sequence codeword which is then stored on a data storage medium.