A code in which each telegraph or data signal conforms to specific rules of construction so that departures from this construction in the received signal can generally be automatically detected and corrected. Note 1: If the number of errors is less than or equal to the maximum correctable threshold of the code, all errors will be corrected. Note 2: Error-correcting codes require more signal elements than are necessary to convey the basic information. Note 3: The two main classes of error-correcting codes are block codes and convolutional codes.