Ok. Thanks both of you for your help. The second process works too, in a way which can be useful for me since all my notes (highlighted parts of texts and annotations) are exported and exploded in Tinderbox.
I think it could really save me time since usually, I have to switch between DT and TBX, write down my notes into TBX, paste or rewrite some parts of texts and add tags. However, the work is not entirely done: I have, of course, to tag each notes since every tag is different from one note to another and, above all, add manually each page number… unless we forge another key ;)) to export each page number as an attribute? I don’t think it would be a judicious choice since I don’t need an attribute for that. It would be perfect if only each page number was inserted within the same note than the text of each note. Anyway, it’s already a great advance in my reading process.