Oh I think I see what you mean. The specific scenario is: 1. External actor A1 sends a request t1 to Spanner 2. Spanner responds with a message m1 confirming

Oh I think I see what you mean. The specific scenario is: 1. External actor A1 sends a request t1 to Spanner 2. Spanner responds with a message m1 confirming t1 is committed 3. Based on receiving m1, A1 sends a private message to external actor A2 4. A2 then initiates a request t2, which affects a set of objects completely disjoint from the set affected by t1. t2 is committed. Now Spanner guarantees that the timestamp for t2 > timestamp for t1. If the set of objects affected by t1 and t2 overlap then PT and Spanner provide the same guarantees (each object can only move 'forward' in PT). But if they affect disjoint sets of objects, then Spanner provides stronger guarantees. Is that correct?