A couple of years ago, a joke made the rounds in Belfast: "How many Provos does it take to change a lightbulb?" The answer was: "None - it's not in the Good Friday Agreement."
It wasn't particularly funny, but it struck a chord because it reflected Sinn Fein's almost mantric attachment to the agreement, and the republican refusal to do anything beyond its terms.
The fact is that, during recent years, the republican movement has exhibited two apparently contradictory characteristics. One is a high degree of flexibility and pragmatism, but the other is a remarkable devotion to certain texts.
While Sinn Fein's primary text has been the 1998 Good Friday Agreement, the IRA's has been its statement of May 2000 which spoke of putting its weapons beyond use. Ulster Unionist leader David Trimble refers to this as a promise but even a cursory glance at the statement reveals thickets of surrounding conditions.
Foremost among these are the issues of policing and demilitarisation, together with more nebulous talk of the creation of the context of an "enduring political process with the potential to remove the causes of conflict." Through all the ups and downs of the last few years, Sinn Fein has stuck, as though by superglue, to the agreement. The IRA has stuck just as firmly to its statement.
Sinn Fein refers its many critics to the part of the agreement which says all parties should use any influence they have to achieve decommissioning. The party argues it has done so, and is thus in full compliance.
Those critics who argued that decommissioning was, at the very least, implicit in the agreement and indeed should be a requirement for participation in democratic structures, were simply referred back to the near-sacred text.
Much of the wrangling over arms comes back to the fact that Unionists did not manage to get into the agreement a clear requirement that the IRA should disarm. Nor did they get London, Dublin or other parties to agree that Sinn Fein be banished from the devolved Belfast government if the IRA did not act.
The problem within Unionism was compounded by the fact that some of those demanding decommissioning never actually thought it was achievable, and were simply using it as an anti-agreement blocking mechanism. This devalued the moral argument that the guns issue was one of principle, being a dispute between pure democrats against unreconstructed terrorists.
The May 2000 IRA statement was hailed as a huge advance on the terrorist organisation's previous position, which was basically one of "not one bullet, not one ounce of Semtex". It offered, however conditionally, the prospect of arms being put beyond use.
Within the republican community, this represented a Rubicon, a huge step both strategically and psychologically. No arms were handed over but they were inspected by outsiders. What had been unthinkable for the IRA had become negotiable.
For Unionists, however, the impact of the May 2000 declaration has long since dispelled. The fact that, as the months passed, no guns were actually put beyond use led to growing Unionist belief that the IRA was involved in a con-job.
But the British and Irish governments have, of late, viewed the May 2000 statement as the key to making progress along the slow and difficult road to decommissioning. Given the emphasis the IRA placed on the statement, it was always a fair bet that it would not happen without moves on policing and demilitarisation.
On policing, there has been another piece of republican holy writ; the Patten report, drawn up by EU Commissioner Chris Patten as an adjunct to the agreement. The Government accepted the report in principle but a great many of its details were changed when Peter Mandelson was Northern Ireland Secretary.
In recent negotiations, the Government has abandoned many of those changes in response to republican arguments that it should get back to the Patten text. New legislation is on the cards to reflect that, the republicans even managed to squeeze out extra concessions that go beyond Patten.
The Weston Park talks, which many assumed were about decommissioning, appear to have been mostly about policing. The Government, with Dublin's backing, committed itself to the idea that the way to decommissioning lay via policing reform.
In other words, it took the IRA at its word, by taking the May 2000 statement as the working text for the negotiations of the past month. Some will be worried at how the IRA has, for the moment, got to the centre of the political world, using its arms to extract other concessions.
Most other participants have recently come to look more like bystanders than forces at the negotiating table. On the Unionist side, this has partly been because decommissioning has become elevated to centre-stage, leaving the issue to be hammered out between the IRA and the Government.
Yesterday's development means the IRA has moved again, for it has never before officially discussed methods by which its arms could be put out of commission. This addresses one requirement of Unionists, who have been demanding to know how it would be done.
But, as yet, there is no answer to the other Unionist demand; just when it would happen. If the IRA does clarify this, it will probably signal the timing will depend on the pace at which the Government moves on policing and demilitarisation.
Since the Government has said new policing legislation is not expected for more than a year, all this is going to take quite a while. In the meantime, the IRA may set out its position in a new statement which will become the latest in its series of venerated texts.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies