What does a referral actually consist of?

It is just the name of another T, or does your old T discuss your case with the new T before passing you on? What about the notes she made? Is there a letter of introduction?

For some patients, there would be insurance documents, payment receipts and maybe other burocratic and financial paperwork.

Would old T warn new T if you were a danger to yourself or others? If you missed a lot of sessions or were unreliable about payment, would old T warn new T about that?