[>] : Shows only files which by comparison need to be copied from left to right.
[<] : Shows only files which by comparison need to be copied from right to left, or (in asymmetric mode) which will be deleted on the right side.
[=] : Shows files which are considered equal with the current compare settings.
[=/=] : Shows files which appear as being different, but with no default copy direction (e.g. same date/time, or date/time ignored).
When one of the directory is an archive, we can get a [?] between the files.

In my case, the files with this [?] sign are equals. So they are not to be looked like the files with the [=/=] sign.
Best regards
