BBC World recently broadcast a 45-minute documentary on Northern Ireland. The producer showed a video of the programme to a friend who, after 20 minutes, asked the producer to press pause. "Just remind me," he said. "I know what the unionists want and who the republicans are. But which sides are the Catholics and the Protestants on?" This man had a first-class degree and read a broadsheet every day. But a blank gaze over Northern Ireland is the acceptable face of ignorance.
At some point, Sydney Elliott realised that he had to hit the pause button, too. The fifth edition of Northern Ireland: a political directory, originally due at the beginning of last year, has been much delayed: after all, we had had the agreement, the referendum, the elections. But in the end, the questions about when, if and how the Belfast agreement would be implemented were left unanswered. One can only wonder about how Elliott must have felt when Peter Mandelson was reshuffled to Hillsborough Castle after the book had gone to press.
Still, Elliott has compiled an indispensable catalogue. Under the rocks of unionism and nationalism crawl a thousand divisions. Most are here. Those that are not deemed worthy of a separate entry are included in the superb index. And you have to wonder whether Elliott is expressing his own exasperation with the politics of petulance when he refuses to give the breakaway Northern Ireland Unionist Party, with four assembly members, its own independent entry.
The directory lists the significant acts of violence of three decades of the Troubles. It begins with the Abercorn restaurant bombing, an attack described as "one of the most horrific" of the entire period. The entry reminded me of the grainy photographs of casualties once shown to me by a smiling member of the Royal Marines who was explaining the damage that can be caused in a restaurant by a "high-velocity table leg".
There are omissions. There is no mention of Vincent McKenna or Sean O'Callaghan, both ex-IRA members who have emerged as sirens on paramilitary violence and decommissioning, particularly in unionist circles. There are inconsistencies. Bairbre de Brun, the headline-dominating minister for health in the Northern Ireland executive, receives a shorter entry than Lady Olga Maitland - and Sinn Fein spinners were saying more than a year ago that De Brun was likely to be one of the two nominated ministers. Furthermore, separate entries on issues such as "decommissioning" might have been useful. Certainly no issue has cast a longer shadow over the recent political process since John Major first used it at the end of 1994.
Nevertheless it is an act of diligence, and a reason for gratitude, that this book exists at all. To go by what I recall of the paper-strewn chaos of Elliott's office in Queen's University, it is indeed remarkable that this gem came to shine out of that rubble. The current uncertainties already suggest an unanswerable case for a sixth edition of the NIPD in five years' time. By which time we may be back to the grim inexorability of guerrilla warfare. Whatever, there will be a whole new set of political questions for Dr Elliott to answer.
Tim Franks is a BBC political correspondent