anchor.diff:  have an id. Probably there will be more elements with an id. But in some cases the costs for that are simply to
   high and the user will also have to use a unnecessary compilcated UI.
   
  -WARNING: At the moment elements with an id of a _historized_ list are not yet implemented. +WARNING: At the moment elements with an id of a _historized_ list are not yet implemented.
positive.code: Elements should _not_ have their own id if
  
  * the elements cannot exists without the containing object
  * it makes on sense to display or edit the elements without displaying or editing the containing object
  * the content of the list should be displayed nearly every time the simple fields should be displayed. This
  can also mean the content is displayed on the same page as the containing object. For example in a ListFormElement
  * there will be not too many (about 5 to 10) elements for one containing object
  
negative.code: they are closely tied to the object holding the list. Elements (objects) without id field cannot be changed, saved or
  deleted directly or independently.
  
  IMPORTANT: If the elements contain an id field the list is lazy loaded. This means every access to the
  list causes a persistence action. This can be very expensive. Also the implemented lazy list don't support
  all the methods an normal list does.
  
  