Asymptotically efficient, binary-compatible block codes for M-ary runlength-limited constraints

We present a new result on the capacity of M-ary runlength limited constraints and use it to construct asymptotically efficient block codes. The codes are constructed from permutation codes and are scalable with respect to M. The codes are useful in high-rate constrained coding and nonbinary optical recording systems that achieve both high density and backward compatibility to binary recording.