Presented herein are systems and methods for checking the integrity of data transmissions between or within one or more digital processing systems by identifying a data characteristic that is likely to change if there is an error in transmission. According to one embodiment, data messages are modified to achieve a selected characteristic according to a predetermined protocol, and changes to the data are recorded in a longitudinal check code (LCC) word, which is used by the receiver to decode the data message and restore the original data.