The FCS has its own versioning system. You can update (edit) facts, without losing the old version. The individual versions differ by the version number at the end of every infoID. With the help of the infoID you can also directly link to special versions (see -> Creating links reference).
Using the modify permissions you specify who can edit a fact. Permissions are always assigned to groups.
The attachments to download facts files are not stand-alone facts (having no versioning or GOE). Read details under: Concerning Download Versions.
Warning
it is possible that several users work in parallel on new versions of
the same fact. These will not merge into one version though. As long as
a version is not yet published, its modified contents are not visible.