anchor.diff:  particular direction, or move in unison or in a coordinated pattern. The
   basic way to create one is to call:
   
  -code,clojure------------------------------------------------
  -code,clojure
  +[source,clojure]
  +----
   (afterglow.effects.params/build-direction-param)
  -------------------------------------------------
  +----
   
   By itself this call would simply return a non-dynamic direction telling
   fixtures to point directly at the audience. However, you will use one or
  
positive.code: = Dynamic Parameters
  James Elliott <james@deepsymmetry.org>
  :icons: font
  
  // Set up support for relative links on GitHub; add more conditions
  // if you need to support other environments and extensions.
  
negative.code: |=======================================================================
  
  Collectively, `x`, `y`, and `z` specify a three-dimensional vector in
  the light show’s <<show_space#show-space,frame of reference>> telling
  the lights which direction they should point. The absolute magnitudes
  of the values are not important, it is their relative sizes that
  matter. The default of `[0, 0, 1]` means the lights point neither left
  nor right, neither up nor down, and straight towards the audience.
  `[1, 0, 0]` would be straight right, `[-1, 0, 0]` straight left, `[0,
  1, 0]` straight up, and `[0, 1, -1]` up and away from the audience at
  a 45° angle.
  
  All of these parameters, except for `frame-dynamic`, can themselves be
  dynamic parameters, such as show <<variable-parameters,variables>>
  (with the convenience shorthand of just passing in the keyword by which
  the show variable was stored) or <<oscillated-parameters,oscillated
  parameters>>.
  
  ## Aim Parameters
  
  Aim parameters are a way to tell a group of fixtures to aim at a
  particular point in space, or track something in unison or in a
  coordinated pattern. The basic way to create one is to call:
  
  [source,clojure]
  ----
  (afterglow.effects.params/build-aim-param)
  ----
  
  By itself this call would simply return a non-dynamic point telling
  fixtures to aim directly at a height of zero, centered on the X axis,
  