The transfer by the author of his rights over his work may be total or partial. It must include for the benefit of the author a proportional share of the revenue from the sale or exploitation.
However, the author’s remuneration may be assessed on a flat-rate basis in the following cases:
1° The basis for calculating the proportional shareholding cannot be practically determined;
2° The means of controlling the application of the shareholding are lacking;
3° The costs of the calculation and control operations would be out of proportion to the results to be achieved ;
4° The nature or conditions of the exploitation make it impossible to apply the rule of proportional remuneration, either because the author’s contribution does not constitute one of the essential elements of the intellectual creation of the work, or because the use of the work is only incidental in relation to the object exploited;
5° In the case of assignment of rights relating to software;
6° In the other cases provided for in this code.
It is also lawful for the parties, at the request of the author, to convert the rights arising from contracts in force into lump-sum annual instalments for periods to be determined between the parties.