What is left to agree in the Brexit Treaty? - BBC News
From the Irish border to data protection to tax information, some key issues are still outstanding on the road to a deal.
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At a press conference in March the Brexit Secretary David Davis and the EU's chief negotiator Michel Barnier unveiled a slideshow of the Brexit Treaty, with the sections agreed by both sides highlighted green.

It amounted to roughly 75-80% of the 129-page document that will seal the terms of the UK's departure from the EU and which is officially called the "Agreement on the Withdrawal of the United Kingdom".

The UK says the deadline for settling the outstanding issues is October, when the agreement will be submitted to the European Parliament. Mr Barnier wants progress on these issues in time for an EU summit on 28 June.

Here is what's left to discuss:

Both sides have committed to avoid infrastructure on the border between Northern Ireland and Ireland.

Brussels has proposed a protocol - nicknamed "the backstop" - which would see Northern Ireland stick to those rules of the customs union and single market that are required for cross-border co-operation to continue.

It's described as an insurance policy in case no other solutions are found.

Britain agrees to the need for a backstop but says this version risks barriers being created between Northern Ireland and the rest of the UK, and so wants an alternative.

This video can not be played To play this video you need to enable JavaScript in your browser. Technology can streamline EU borders but they are not frictionless.

Known in the trade as "governance" this is an item that sounds boring but which Michel Barnier says could bring the whole deal down: how to solve disputes between the UK and the EU arising as a result of the treaty?

The EU has proposed a Joint Committee made up of representatives appointed by London and Brussels. If they can't solve a problem, it would be referred to the European Court of Justice.

The UK government likes the idea of "J-Com" but not of judges in Luxembourg having the final say.

A complicated compromise to oversee the governance of the citizens' rights part of the deal hasD been agreed, though.

Then there is a swathe of subjects known as Other Separation Issues (OSI's).

The EU is proud of its rules that protect regional products so that champagne can only come from Champagne, Manchego cheese can only come from La Mancha, Cornish pasties from Cornwall.

Brussels wants this system written into British domestic law. The Brits agree with the concept but aren't sure about the method and want to ensure it applies to British products in the EU too.

Some in the food and drink industry suspect some ministers view this as a measure to protect European industries that would limit the UK's room for manoeuvre in future trade talks with other countries.

There are still disagreements about how both sides will work together on on-going police and judicial matters.

For example, the EU says that the European Court of Justice should be able to pass judgements that have an effect in the UK after the end of the transition period in cases where events occurred before the end of the transition period.

On security, the UK thinks that co-operation on extradition, the British relationship with the EU crime-fighting agency Europol and the sharing of criminal records should be the subject of a separate security treaty which the two sides should begin negotiating straight away.

The EU wants the European laws that are mentioned in the Brexit Treaty to continue to apply in the UK in the way they do now.

This is the legal concept of "direct effect" which is at the heart of the argument over the supremacy of EU law.

The UK government has agreed to write the Withdrawal Agreement into domestic legislation but is still working on the details of how to do this, before it's voted on by MPs.

Remember the huge political row in Summer 2016 over the UK's departure from the EU's nuclear energy watchdog Euratom?

Most issues related to it have been settled, apart from who will own certain radioactive material that remains in the UK - Britain or the EU countries where it originated?

The signals are that a deal is close on this highly technical matter.

British companies hold all sorts of personal data belonging to EU citizens, and the European Commission thinks that European data protection law should continue to apply to it after Brexit.

The UK would like a comprehensive deal on data sharing with the EU as part of the discussions about the future relationship, and is wary of agreeing divorce-related measures that could tie its hands.

There's a section about how to handle government tenders for goods and services which will be underway during the Brexit process - so called "public procurement". Think new British passports being made by a Franco-Dutch firm.

Most of it has been agreed, but one jargon-filled paragraph stands out as unresolved.

It concerns the rule which says new contracts should be open to companies across the EU. Public procurement lawyers suspect the UK is waiting for a guarantee that British firms will be able to bid for European government business if British contracts remain open to their continental competitors.

The EU wants the UK to share customs data for three years after the end of the transition period, and information about certain taxes for five years after the end of the transition period.

And there are some other unresolved technical issues scattered throughout the document that test the knowledge of even the most seasoned Brexit geek.

But small details could have a big effect because the whole lot has to be agreed for the deal to be signed off.
• None What happens now that a deal's been done?