n Setting up an assembly of 90 elected members to run Northern Ireland affairs, within the constitutional framework of the United Kingdom.
n The so-called North-South dimension, bringing the Irish Republic and Ulster together through cross-border bodies with defined but limited powers
n The East-West relationship, bringing together Dublin, Britain and Northern Ireland into a consultative Council of the Isles, inclusive of the Scottish and Welsh assemblies.
n Changes to Articles 2 and 3 of the Irish constitution which lay claim to Northern Ireland to be party of the republic.
If a "historic compromise" can be reached, it will be put to separate referendums of the people north and south of the border on 22 May. It must then by approved by the British and Irish parliaments.
The talks have been going on, with long gaps, for more than two years, since John Major and Albert Reynolds produced the Downing Street declaration. Tony Blair has taken up where his predecessor left off, injecting a new note of urgency with his "settlement train is leaving" speech soon after taking office.
But the main talks are going on in Belfast, where the Ulster Unionists led by David Trimble, John Hume's nationalist SDLP and Sinn Fein are locked in negotiations on a draft settlement being "synthesised" by the talks chairman, former US Senator George Mitchell. He failed to meet his own deadline of Friday night to produce a constitutional blueprint for the future of the province, but hopes to do shortly.
Gerry Adams, Sinn Fein's president, accepted that a paper would be tabled and promised "then we will knuckle down and get into negotiations". Republicans insist they must be party to any peace deal, but the rules of the talks process allow for an agreement between the two major parties to go before the people. Ian Paisley's Democratic Unionist Party has remained outside the talks, oblivious to the pleas of Secretary of State for Northern Ireland, Mo Mowlam.
The biggest sticking points are the scope and powers of a north-south ministerial council through which Dublin and Belfast can co-operate in future. Mr Mitchell is believed to have recommended at least six implementation bodies, which might have executive powers. The Unionists would oppose such powers, but the Irish government insists that the bodies have real clout.
Another problem is the reluctance of the Irish government so far to spell out how it will abolish the republic's claim to the six counties of Northern Ireland.
But progress has been made on the setting up of an elected assembly to replace the Unionist-dominated Stormont parliament, abolished when direct rule from London was introduced more than 20 years ago. Mr Mitchell is understood to favour an amalgam of Mr Hume's ideas for a power-sharing executive, plus a system of committees favoured by the Ulster Unionists. This is acceptable to the main parties.