anchor.diff:  |=======================================================================
   
   Collectively, `x`, `y`, and `z` specify a three-dimensional point
  -within the light show’s [[frame of reference|show-space]] telling the
  +within the light show’s <<show_space#show-space,frame of reference>> telling the
   lights where to aim. When this vector is supplied to an
   <<effects#aim-effects,Aim Effect>>, it causes the attached lights to
   make the specified movement, if they are capable.
  
positive.code: 
  The rotations requested by `pan` and `tilt` jointly identify the
  direction the light should turn away from the audience. The result of
  the parameter is a direction vector in the light show’s [[frame of
  reference|show-space]] telling the lights which direction they should
  point. When this vector is supplied to a
  <<effects#direction-effects,Direction Effect>>, it causes the attached
  lights to make the specified movement, if they are capable.
  
  
negative.code: 
  A more traditional way of aiming fixtures involves setting pan and
  tilt angles. Afterglow supports this approach as well, although even
  in this case you use angles expressed in the standard show
  <<show_space#show-space,frame of reference>> regardless of how the
  individual fixtures are hung. Pan Tilt parameters are an alternate way
  to work with <<effects#direction-effects,Direction Effects>>. The
  basic way to create one is to call:
  
  [source,clojure]
  ----
  