21. A communications network, comprising: a plurality of nodes, wherein information is transmitted between nodes in the form of a data word representing the information and a check word for error detection, wherein said data word and said check word include a plurality of code symbol groups; wherein as a data word symbol group is received at a node, said symbol group is modified to produce a modified data word symbol group; first means for processing said data word symbol group and said modified data word symbol group and for producing a comparison symbol group in response thereto; means for encoding said comparison symbol group to produce an encoded symbol group; second means for processing said encoded symbol group and said check word symbol group after each encoded symbol group is produced to produce a modified check word symbol group, wherein said modified check word symbol group conforms with said modified data word symbol group; and wherein said modified data word symbol group and said modified check word symbol group are transmitted to another node.
21. A communications network, comprising: a plurality of nodes, wherein information is transmitted between nodes in the form of a data word representing the information and a check word for error detection, wherein said data word and said check word include a plurality of code symbol groups; wherein as a data word symbol group is received at a node, said symbol group is modified to produce a modified data word symbol group; first means for processing said data word symbol group and said modified data word symbol group and for producing a comparison symbol group in response thereto; means for encoding said comparison symbol group to produce an encoded symbol group; second means for processing said encoded symbol group and said check word symbol group after each encoded symbol group is produced to produce a modified check word symbol group, wherein said modified check word symbol group conforms with said modified data word symbol group; and wherein said modified data word symbol group and said modified check word symbol group are transmitted to another node. 25. The communications network of claim 21 wherein the means for encoding encodes each symbol of the comparison symbol group using the same encoding scheme as used for the data and the check words.