Are space stations compatible?

Question

I know that there are (at least) two space stations in operation: The ISS and the Chinese one (which I don’t remember the name now)

Imagine, that China, EU, Russia and USA agree on cooperating in the space and they decide to join the Chinese space station and ISS together.

Would this be possible? I mean, would airlocks "match" together and could they be joined together?

I am basically asking, if there is any recognised "standard" in how to build spacecraft. So, if tomorrow this happens could it be possible?

• India delivery ship successfully landing on ISS or Chinese Space station
• The same the opposite way: Russian Progress ship landing on China space station
• Any thinkable cross-joining of space ships

Answer 1

The International Space Station's PMA docking adapters and Tiangong-1 both use passive APAS-95 docking adapters for spaceship operations; the ISS additionally uses CBM connectors for connecting modules (including most supply spacecraft) and Soyuz probe-and-drogue connectors for Russian modules and craft.

To cover your scenarios:

1. Connecting two APAS adapters requires at least one of them to be an active adapter, so the two stations can't dock, but a vehicle with an active APAS adapter can dock with either.
2. If India makes a delivery ship with an APAS or CBM connector, yes.
3. Progress uses the Soyuz probe-and-drogue system rather than APAS, so no.
4. Mostly not without an adapter.