anchor.diff:  +
   This allows the module to find which taxonomies are applicable to the domain object.
   
  -* implement the `SubtypeProvider` SPI interface: +
  +* implement the `ClassificationRepository.SubtypeProvider` SPI interface: +
   +
   [source,java]
   ----
  
positive.code:         }
      }
  }
  
  ----
  <1> extend from `Classification`
  <2> the type-safe reference property to the "classified" domain object (in this case `DemoObject`).  In the RDBMS
  
negative.code: 
  The following http://yuml.me[] class diagram highlights the main concepts:
  
  image::http://yuml.me/de618edc[link="http://yuml.me/de618edc"]
  
  (The colours used in the diagram are - approximately - from link:https://en.wikipedia.org/wiki/Object_Modeling_in_Color[Object Modeling in Color]).
  
  