a code word includes a first group of data bits and includes code bits that represent a second group of data bits . one embodiment of the code word has a minimum probability of bit transitions among its bits . another embodiment of the code word includes a parity bit . unlike conventional codes , a code that includes such a code word can have both a high efficiency and small error propagation . additionally , by including fewer bit transitions , a sequence of such code words causes less read noise , and thus causes fewer read errors as compared to sequences of known code words . moreover , the code word can include a parity bit to allow improved error detection as compared to known error - detection techniques . therefore , such a code word can significantly increase the effective write and read speeds of a disk drive .