BRUSSELS, Belgium (AFP) — The European Commission and the British government let out an audible sigh of relief on reaching a deal on Brexit divorce terms.

Yet numerous questions remain over Friday’s initial agreement, even before the talks enter a new phase at a December 14-15 Brussels summit.

The terms agreed on Friday cleared the way for Britain and the remaining 27 EU countries to move on to a second phase of talks on issues including their future trade relationship.

But the EU’s chief Brexit negotiator Michel Barnier warned that even regarding the issues wrapped up in Friday’s deal, “there is still work to be done on it, to consolidate and clarify it.”

Britain’s Brexit Secretary David Davis further muddied the waters Sunday by saying London will not honour financial commitments agreed in Brussels without a trade deal — directly contradicting earlier comments by finance minister Philip Hammond.

“No deal means that we won’t be paying the money,” Davis told the BBC.

“It is conditional on getting an implementation period, it is conditional on a trade outcome.”

The preamble to the 15-page divorce deal agreed by British Prime Minister Theresa May and European Commission President Jean-Claude Juncker illustrates its precarious nature.

“Nothing is agreed until everything is agreed,” says the introduction to the text.

Elements of Friday’s deal still open to question are the thorny issue of the Irish border post-Brexit, the sum of money Britain must pay on leaving and the protection of expats’ rights.

The deal is clear on guaranteeing the post-Brexit rights of Britons already living in the bloc and of their EU counterparts based in Britain with family members able to claim residence.

But there is no mention, for example, of future spouses.

“We demand before we can give green light to the withdrawal agreement, that… the future free movement and residence of UK citizens will also be guaranteed and this in all 27 Member States,” said Guy Verhofstadt, leader of the liberals group in the European Parliament.

Regarding citizens’ rights, the divorce bill text indicates Britain will bring forward a bill to incorporate them into British law.

But it is not clear what will happen if Westminster one day repeals that bill.

“Any change by UK parliament to citizens’ rights will be very visible and can only happen via express repeal of treaty,” tweeted Stefaan de Rynck, a member of the EU negotiating team.

There is also ambiguity over the exact size of the financial divorce settlement, despite an agreed methodology to determine how deep Britain must delve into its pockets.

“We cannot calculate exactly the sums in question — all these figures will fluctuate,” said Barnier. Unofficial EU estimations are in the order of 60 billion euros ($70 billion).

Britain puts the sum at between 40 and 45 billion euros.

The issue of the border between Northern Ireland and the Republic of Ireland almost scuppered the deal.

The were concerns in the North that Britain was headed for a deal entailing a hard border separating it from the rest of the United Kingdom.

Britain says that if need be it would propose “specific solutions to address the unique circumstances of the island of Ireland”.

These include alignment with the Internal Market and the Customs Union rules, while respecting the terms of the 1998 Northern Ireland peace agreement.

“The language on ‘full alignment’ means different things to different people,” however, Jonathan Powell, chief of staff to former British prime minister Tony Blair, told the Financial Times.

“A series of contradictory undertakings have been given and a new separate strand of negotiation on Ireland opened in the next stage.”