Nested block decodable runlength-limited codes

Consider a d k RLL constraint that is contained in a d k RLL con straint where k d and d and x a codeword length q k It is shown that whenever there exist block decodable encoders with codeword length q for those two constraints there exist such encoders where one is a subgraph of the other furthermore both encoders can be decoded by essentially the same de coder Speci cally a d k RLL constrained word is decoded by rst using a block decoder of the d k RLL encoder and then applying a certain function to the output of that decoder