A concatenated coding scheme for error correction in (0, k) constraint channels with hard and soft decision decoding is presented. It is based on a Reed-Solomon code as an outer code and a runlength limited code obtained by modifying a binary linear transparent block code as an inner code. Soft decision decoding of the concatenated codes presents a coding gain of about 3dB over hand decision decoding. 259 Immink, K.A.S., Runlength-limited sequences (1990) Proc. of the IEEE, 28 (11), pp. 1744-1759. , NovGarcía, E.M., Baldini, R.F., A method to find runlength limited block error control codes (1997) Proc. of ISIT97, Ulm, Germany, p. 220Honary, B., Markarian, G., (1997) Trellis Decoding of Block Codes: A Practical Approach, , Kluwer Academic Publisher