Yes, Starnet is one of the few current Star Alliance-wide pieces of software. (note that "piece of software" can quite correctly be abbreviated as POS in this context!) Think of it as the interchange network for FF awards between all the *A carriers.

However obviously each carrier can program its own interface to it or otherwise set configurations on it, and the legendary "evil UA starnet programmer" has blocked much award availability on other *A airlines from being visible to UA reservations agents.

Or think of it like one of the big ATM interchange networks like Plus or Cirrus. But add to it the lovely feature of "I'm sorry, your bank account does not exist" when trying to use a different bank's ATM