It seems to me that they work something like this:
- Combatants: Individual PCs, NPCs, and monsters.
- Groups: A particular cluster of combatants; a group of monsters in a single room, for example, or the party of PCs.
- Group Sets: An adventure or campaign cluster of Groups?
- Encounters: A distinct event that includes groups and/or combatants.
And are there still plans for being able to save individual combatants as files?