It has to do with the legislation in France on the "35 heures" - the 35 hour working week.
Because it is not so easy to account for the hours worked by management personnel, they invented a whole series of new categories, like "cadre autonome", "cadre forfait heures" , etc. to cover all eventualities to, roughly speaking, ensure that all management categories work every hour that God sends without time off in lieu or overtime - sorry to be sarcastic but a lot of us got right royally "scr**ed"with this so-called advantage.

As to how to translate, I think you have to leave it in French perhaps with an explanation and certainly in inverted commas

http://emploi.journaldunet.com/php/publication/publication.p...