Method 1

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Method 2

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Method 2 seems more intuitive than method 1:

    ==> We express the semantic directly in ER
    ==> Code can be generated directly by ATOM3
    ==> Instance of entities can be seen as objects
    ==> Default appearance can be set and all the constaints can be kept

Still, Method 1 may be usable, I will have to think about it... Return