What's the workflow after you work on it? In particular, does it need to go back to someone still working in FM7, for any future work?
FM7 is pre-Unicode, and the process of opening it in any later FM version results in changes that are not trivially reversed, even if you save as MIF (which is always required when handing work back to earlier versions).
Merci pour votre aide, j'ai pu télécharger la version du programme dont j'avais besoin mais il n'y avait que des mises à jour pour la version 7, j'ai donc récupéré la version 8 !
re: Thank you for your help, I was able to download the version of the program I needed but there were only updates for version 7, so I got version 8!
FM8 should be able to save-as (binary) to either version7 or version 8, in addition to being able to save as MIF 8 or MIF 7. However, FM8 supports Unicode, and may well be making changes upon opening an FM7 document; changes not trivially portable back to FM7.