Subject to change, but here's a first pass of what I worked on today:

What I've done so far:

Joining/Leaving clan GDI:

- Clans that join ClanGDI can't leave for 72hrs
- Clans that leave ClanGDI can't rejoin for 48hrs (lengths are subject to change)

Attacking:

- If either the defender or attacker is in Clan GDI, all attackers must declare war on the defender
- If the attacker is in clan GDI:
 -- The defender must have attacked the attacking country sometime during the round OR the defender must have attacked the attacker's clan within the last 72hrs
 -- OR the defender must be untagged
- If (the attacker is not in clan GDI OR the attacker/defender relationship meets the above criteria) AND the defender is in clan GDI:
 -- The defender must meet the minimum military requirements posted above (stubbed for now) or they don't receive protection

Haven't built this, but I need to add it:
Spyops:

- Countries in clan GDI can't do or be subject to harmful ops, period. This is a bit of a technical limitation in how we store spyop data and will need to be revisited :(

Detagging/leaving tag:

- Countries who leave or are booted from a tag that is in clan GDI cannot join or create a clan for 72hrs of the detag event

Note: no restriction on types of attacks you can do