See EU website
Cash then talks about changes to the "Common Rule Book" but that's just a line Downing Street made up. Anyway it was part of Chequers and this withdrawal deal is different
This piece suggests an important point has yet to be appreciated -
We are not obliged to follow new EU laws if we are in the Backstop (neither in Great Britain nor Northern Ireland).
Harmonisation is only required on state aid and competition policy