Carlos, the short answer is that identity owners can write their own claim definitions to the Sovrin ledger and then write instances of those claim definitions to the ledger. So it’s inherently extensible.
That said, if there are hundreds or thousands of different claims definitions, we’ll have a Tower of Babel. So a distributed ledger for self-sovereign identity definitely raises the stakes for semantic interoperability.
There’s a lot of discussion going on about this right now, so please feel free to share any thoughts you have about how you prefer to solve this thorny issue.