-------------------------------------------------------------------------------
 Rules about UML models:
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- Naming rules :
----------------
    Following rules are mandatory for all 'name' attributes of UML elements :
    
      A name attribute must :
      - only contain letter and digit characters 
          => all other characters are forbidden : punctuation symbols ...

      - respect case (case sensitive)
      - not exceeds 30 characters
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- concrete classes are final, i.e. do not have sub-classes.
Alternatively, only abstract classes can have sub-classes.
Motivation: ...
---


- If no cardinality is defined on an attribute it is assumed to be "1"
Motivation: ...
----



- If no cardinality is defined on a collection it is assumed to be "*"
Motivation: ...
----

- If no cardinality is defined on a reference it is assumed to be "1"
Motivation: ...
----



- other constraints may be introduced on attributes: 
  - maxLength on string types.
  
- @@TODO we need to decide where we put the documentation of references and collections.
It may be best to do so on the property corresponding to the navigable association end representing these two concepts
in our profile @@