anchor.diff:  to match them up with the manual.
   
   |:fine-offset
  -
   |There is one circumstance in which there _will_ be gaps in the
   `:offset` values for your channel definitions. Sometimes a pair of
   channels are used to express a single value, such as pan, tilt, or a
  
positive.code: |Purpose
  
  |:channels
  
  | A list of channel specifications which tell Afterglow about the DMX
  channels that this individual head responds to. These have exactly the
  same structure as the channel specifications for the main fixture, as
  
negative.code:  other function range defined for the channel.
  
  |:end
  |The end of the function range: the highest DMX value which activates
   this function on the channel. Must be a legal DMX value, from `0` to
   `255`, and greater than or equal to `:start`. Ranges must not
  