anchor.diff:  You can use any Variable as the Coordinate Transform Variable; here’s an
   example using the vertical Coordinate Axis to hold a vertical transform:
   
  -[code,bash]
  +[source,bash]
   ----
   dimensions:
      y = 428;
  
positive.code: Coordinate variables created this way are used for implicit
  *_CoordinateAxes* processing (next section). Example:
  
  [code,bash]
  ----
     double valtime(record);
       :long_name = "valid time";
  
negative.code: 
  === Example 3: Multiple Coordinate Systems
  
  [source,bash]
  ----
  dimensions:
     y = 428;
  