Article 50 TEU says:
The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.
And "The Treaties" is defined as:
the present Treaty (TEU) and on the Treaty on the Functioning of the European Union
So both these treaties cease to apply. But if there are other UK/EU treaties, might they continue to have effect? Are there any other such treaties?
For example - the other such treaties (if they exist) might be "downstream" from these main two, and hence no longer apply.