what are the valid version-to-version upgrades for fedora?

followup to earlier post but different enough that i'll start a new thread: using f30 and f31 as examples, what are the valid version-to-version upgrades using "dnf system-upgrade" that will both: 1) do the appropriate upgrade, and 2) allow normal, subsequent "dnf update" operations? i'm perusing this page: https://fedoraproject.org/wiki/DNF_system_upgrade so here's how i interpret that. first, it's trivially obvious that one can upgrade from an official (possibly updated) f30 to an official f31 (once it is released), so that one's easy. (that scenario involves strictly official releases, no pre-release or branching.) next (what i asked about earlier), if i install from scratch a current, branched f31 iso image -- say, from here: https://kojipkgs.fedoraproject.org/compose/branched/latest-Fedora-31/comp... that will definitely give me a branched version -- will it allow me to subsequently update to keep up with changes on the way to f31, and will that allow me to finally system-upgrade officially to f31? finally, if i have a (fully-updated) f30 system right now, before f31 comes out, can i "dnf system-upgrade" to move up to the current "branch", and eventually upgrade to the official f31 when it comes out? just trying to understand the valid possibilities. rday