The UK Government has published how it plans to deliver on the obligations accepted when the special Protocol for Ireland and Northern Ireland on relations between the EU and the UK was agreed as part of the Withdrawal Agreement on EU membership.
Reflecting both the letter of the agreement as well as the spirit of "taking back control", the UK Government has emphasised that Northern Ireland's trade and commercial relationships as part of the UK remain essentially undiminished.
That is correct, but only part of the story.
In the remaining months of 2020 there is a complex series of operational and legislative decisions still to be taken to implement the protocol. An important starting point is an acceptance that the Brexit argument is over.
For better or worse, from January 2021 Northern Ireland will have unique status in both the UK and in relation to the EU. The protocol gives Northern Ireland businesses special treatment when trading with GB and when trading north-south on this island.
The arrangements are potentially a little more burdensome but, for many businesses there are worthwhile advantages.
There are potential difficulties. Goods coming into Northern Ireland which may be consigned to places south of the land border should pay EU customs duties as if landing in Northern Ireland was a formal entry to the EU.
The protocol describes the process as identifying goods which are 'at risk' of being consigned south of the border.
The mechanism that adjudicates the 'risk' becomes an important decision. The goods deemed to be 'at risk' must be documented in a process that separates them from goods arriving in Northern Ireland to stay in the UK.
The statement by the UK Government that there is no need for a separate customs infrastructure, to administer EU procedures at Northern Ireland ports, stands alongside the question of how the EU's external frontier can be managed.
The UK wants minimal formalities and, in turn, believes that customs duties paid on the 'at risk' goods should accrue to the UK customs authorities.
It remains to be seen whether this UK decision will survive the still unfinished negotiations on the Withdrawal Agreement.
There is still a serious possibility that the current negotiations UK-EU will not produce an agreement.
For Northern Ireland, that failure will add new complexities.
In the absence of a UK-EU agreement, and then with a resort to WTO conditions, the special Northern Ireland - Ireland Protocol will remain in place.
The formal content of the protocol is now legally binding as an agreed part of the EU Withdrawal Agreement.
For businesses, from both parts of the island, it is important that debate should focus on how to maximise the benefits of the protocol, even when it may be imperfect.
The scope for potential improvements has been demonstrated in a recent publication by Queen's University academics, led by Dr. Katy Hayward and Prof. David Phinnemore.
They have examined the arrangements for the evolution of the Protocol through an agreed review by a Joint Committee (EU and UK) which will have a continuing supervisory role.
A Specialised Joint Committee, when dealing with issues affecting both parts of Ireland, will have people from both administrations at the negotiating table.
They conclude that the review role "is potentially pivotal to the future governance of Northern Ireland, including in relation to its position vis-à-vis both Britain and Ireland".
It now becomes critical that improving the impact of the protocol is seen as meritorious to all parties and not as a continuation of the former Brexit arguments.
In parallel to dealing with customs processing, the Joint Committee must agree the scale of aid for agricultural subsidies in NI, the application of the VAT and excise rules and the criteria to assess which goods are 'at risk' to attract EU duty on entry at NI ports.
A special arrangement to allow NI service sector businesses to function is still to be agreed.
A long list of regulatory legislative measures for both Westminster and Stormont is queuing for consideration.
Further implementing arrangements for the Protocol are now both urgent and complex.