I'm "rusty", but under the old CTC, you would, of course, be talking to dispatchers on the division you're on, proceed according to signal indication (you can't enter a block anyway without either an "Approach prepared........." or a full "Green" board) and, if you were crossing onto another division, you would receive what was called under OUR operations, a "Form 23A" (permission to proceed past open station and Train Order signal). This would be handed up with any additional orders by the TO operator. On a busy division, there were usually PLENTY of orders from "running" orders, to "High & Wide" to "maintenance" orders ("approach prepared to STOP short of MP 106.5 and do not proceed until contacting MOW foreman Jones that the way is clear)". They would usually be talking to the dispatcher(s) well prior to aproaching a division change, and the transition would be smoothe. I "
think
(and it's been a LONG time since I was an Operator) there WAS an order that went with this, but it didn't specify directly it was a division change, but it merely stated that, "Train # 134 is to proceed from (XXXXXX) to (ZZZZZZZZ) not protecting against other trains (which meant it was the superior move and other trains had to clear up for it). Lord, I've forgotten so much of this stuff!!!!
All of this is, of course, on Southern/ Norfolk Southern!
GF