Gateway network communication backward compatibility

Hi Forum!

Do any one know how far back Gateway comms will be compatible?

We have an enterprise architecture with one central Gateway and 9 sites communicating via Gateway comms.

We would like to upgrade to 8.1 at the enterprise level bit keep the sites on their respective versions( I think the have 7.9.12)

Thanks!

7.9 and 8.1 gateways can connect to each other, but there are compatibility limits. Projects and project resources cannot be transferred between 7.9 and 8.1 (in either direction). Tag values can be read across the gateways, but the tags themselves cannot be remotely edited. So it really comes down to what your gateway network is being used for. As always, we strongly recommend that you set up development environments to test 7.9 to 8.1 compatibility before attempting any production upgrades.

Would a V8.0 Server be able to retrieve tag and historical info from a V8.1 site server via gateway?
Thus, upwards compatible too?