Abstract: In a multi-track record carrier the data is stored in words which comprise an increased number of smybols as a result of added redundancy. In order to neutralize so-called burst errors, the symbols of a word are stored in a distributed manner, for example by interleaving. In the case of loss of track, a regrouped word may then actually consist of parts of two or more different words (i.e. words situated on several tracks). Decoding of such a word is prevented in practice in that a series of symbols are invalidated in the case of loss of track, for example by inversion or by means of an invalidity flag.

Abstract: For the decoding of a data stream which is word-wise protected against errors by a double Reed-Solomon code with symbol-wise interleaving over the code words, first the reliability information for the constituent symbols is aggregated for a code word. Therefrom the strategy is determined, entailing the number of erase symbols and the maximum number of error symbols to be corrected. The correction result is compared with a reliability code and on the basis thereof all symbols obtain an at least trivalent secondary reliability indication for decoding in the second code.