In a method for coding a packet of information words into a frame for transmission, blocks of input data are received, the input data including control words and the packet of information words, the packet having (a) a start preceded by ones of the control words and (b) an ending followed by others of the control words, the blocks being smaller than the packet. When the block consists exclusively of information words, a one bit block header having a first sense is appended to the block to form the frame. When the block does not consist exclusively of information words: the block is condensed to accommodate a TYPE word, the TYPE word is inserted into the block, and a one bit block header having a second sense, opposite to the first sense, is appended to the block to form the frame.