of data are stored across tracks in encoded form using an error correcting code such as a reed solomon code this provides a level of data redundancy in an information theoretical sense between tracks such that if one or more of the tracks contains errors redundant information in other tracks can be used to correct the error 0037 fig4 is a graphic representation of how an error correcting code such as a reed solomon code can correct errors in a multi track data storage medium in accordance with a preferred embodiment of the present invention block 400 is a block of data block 400 comprises four units e g words bytes nybbles etc of raw data using an error correcting code these four units of data are transformed into block 402 which contains six units of encoded data the key to an error correcting code is that to recover the original data not all of the encoded data is needed thus if some of the encoded data gets corrupted or lost the original data may still be recoverable if enough units of the encoded data are intact in a multi track data storage medium it makes sense to place each of the units of encoded data on separate physical tracks since physical corruption of the media may be confined to particular physical locations on the tape thus some tracks of a multi track medium may become corrupted while others remain unaffected for example in fig4 any four out of the six units of encoded data are all that are needed to recover the original data.