As I promised long ago I will write a bit of documentation, in fact what is to be incorporated in the page you are pointing at.
I have never changed the wiki and I am not sure how to do, let me check, I believe it is documented somewhere.The backup policy is checked and applied when a project is saved on the only files concerning this project.
There are 2 different behaviors to name the backup files.
- Using extension .FcStd<n>. <n> is a number that rotates every time the project is saved. It is the historical solution and the default behavior of the current version of FreeCad.
- Using extension .<date-time>.FCBak . This is a new feature introduced in version 0.19 of FreeCad.
Note that if the backup name chosen fits with an existing file an extra-<n> is added to avoid conflicts.
In both cases FreeCad keeps the number of files requested and removes the extra oldest files, even if the policy has been changes in the mean time. Note that it may then reduce the number of backups of the project files to fit the configuration applicable at the time the project is saved.
The parameter “use date and FCBak extension” allows to switch from one to the other policy.
The format of the date can be chosen by the user and is stored in parameter Date Format.
The description of the format can be found here in C++ documentation of strftime function here.