anchor.diff:      inherit content;
     };
   
  -  # Create a "ThenElse" property which contains choices which can choosed by
  +  # Create a "ThenElse" property which contains choices being chosen by
     # the evaluation of an "If" statement.
     isThenElse = attrs: (typeOf attrs) == "then-else";
     mkThenElse = attrs:
  
positive.code:   /* mkOverride */
  
    # Create an "Override" statement which allow the user to define
    # prioprities between values.  The default priority is 100 and the lowest
    # priorities are kept.  The template argument must reproduce the same
    # attribute set hierachy to override leaves of the hierarchy.
    isOverride = attrs: (typeOf attrs) == "override";
    mkOverride = priority: template: content: mkProperty {
      property = {
  
negative.code:           mkNotdef
        ) prioValList;
  
  }
  