Brexit: Why a transition period may not buy more time for talks
So the focus of the Brexit talks has shifted slightly as a result of the EU leaders' summit in Brussels.
There is still plenty of tough bargaining ahead in the next few weeks, especially on the question of money.
But there is also going to be more and more talk about preparing for a transition period - for what happens immediately after the UK leaves the EU in March 2019.
Plenty of people see transition as a way to buy a little more time to sort things out - to finalise negotiations on a future trade deal. But the UK government prefers to calls the transition phase a "period of implementation".
It is not entirely clear what would be implemented.
But the Brexit Secretary David Davis warned this week that without a final deal on a future partnership with the EU - at least in principle - the government would not want to trigger any kind of transition at all.
Does it mean the two sides view the prospects for transition very differently?
The EU27 - the other member states without the UK - have now agreed to start working on new guidelines for their negotiators.
And both the EU and Theresa May (in her Florence speech) have said that any transition/implementation period would take place under "the existing structure of EU rules and regulations".
There will be plenty of technical challenges: what happens, for example, to the UK's role in EU trade agreements with third countries? Those third countries might have their own opinions about that.
But there is also the question of what happens during a transition period itself?
It could mean roughly two more years to continue negotiations on the details of a future partnership with the EU on trade, security and a host of other issues.
The Confederation of British Industry, for example, argues that in order to avoid a "cliff-edge" Brexit, negotiations on a trading agreement should continue during a transition.
But UK government policy is rather different. It still argues that a deal on our "final relationship" with the rest of the EU can be completed before the UK leaves the EU at the end of March 2019.
Most observers are convinced that, for practical reasons, that will not be possible - there is simply too much to do.
Upping the ante
But Mr Davis insisted in the House of Commons this week that if the broad outlines of a permanent deal are not in place when the UK leaves, a transition period will not be triggered.
Asked by Conservative MP Rishi Sunak for reassurance that "what is meant to be a transitory state of affairs does not become a permanent bridge to nowhere", Mr Davis said: "We will try to get the nature of the implementation phase agreed as soon as possible, so that businesses can take that into account."
He added: "But he's right that such a transition phase would only be triggered once we've completed the deal itself, we cannot carry on negotiating through that - our negotiating position during the transition phase would not be very strong."
In other words, Mr Davis is saying - in stronger language than the government appears to have used before - that if there is no final deal by March 2019, at least in principle, then the UK would not want to trigger a transition period.
The words "at least in principle" contain a fair amount of wiggle room. And the EU itself would be delighted if the outlines of a future agreement could be agreed so quickly.
It says only that a withdrawal agreement (as opposed to a future trade agreement) has to be finalised in order for there to be a transition. And Article 50 simply says the withdrawal agreement must "take account of the framework for a future relationship".
But Mr Davis appears to be upping the ante. "No final deal" equals "no transition" equals "hard Brexit".
As a negotiating tactic, it may be designed to keep the pressure on. But it may not be what many business leaders want to hear.