old_contents: control_tokens = [0b1101010100, 0b0010101011, 0b0101010100, 0b1010101011]
  channel_layout = [("d", 8), ("c", 2), ("de", 1)]
  
new_contents: control_tokens = [
      # Control tokens are designed to have a large number (7) of transitions to
      # help the receiver synchronize its clock with the transmitter clock.
      # Control tokens are encoded using the values in the table below.
      # 9........0     C1  C0
      0b1101010100,  #  0   0
      0b0010101011,  #  0   1
      0b0101010100,  #  1   0
      0b1010101011,  #  1   1
  ]
  
  channel_layout = [("d", 8), ("c", 2), ("de", 1)]
  
subject: Document the control tokens.