anchor.diff:  
       #!/admin/users/showHistory?id=4711&startDate=2017-01-01&endDate=2017-01-31
   
  +When this mode is used, a parameter's identifier must only be used once per action mapper tree. This is because a concrete parameter value could not be assigned to the correct action mapper otherwise.
  +
   == A First Simple Scenario
   
   Now that we have learned about the basic classes and concepts of this library, we'll put our knowledge to use and start building URI action mapper trees. We will start small and begin with the simplest possible mapper tree.
  
positive.code: mapSubtree("adminArea", "admin").onAction(GoToAdminAreaActionCommand.class)
  ----
  
  Here we define the mapper name `adminArea` and the path segment name `admin`.
  
  == Adding Parameters
  
  == Writing URI Action Commands
  
  == Generating Parameterized URI Fragments for Links
  
  // TODO: explain URL encoding and decoding
  
  == Configuring the URI Action Mapper Tree
  
negative.code: 
  What does that mean? While this URI fragment structure is perfectly valid, we are not allowed to construct it in the way shown. We must not reuse the mapper name which is defined with the methods `map()` and `mapSubtree()`. This mapper name serves as a unique identifier of a URI action mapper object. Therefore, a mapper name must only be used once per action mapper tree.
  
  What we need to do in this case is to separately define the mapper name for the action mapper and the path segment for which it is responsible. The methods `map()` and `mapSubtree()` we used until now conveniently set these two values to the same String, which is the one we passed as a parameter to these methods. We now have to do without this convenient feature and define both the mapper name and the path segment name for which the mapper is responsible separately:
  
  [source,java]
  ----
  