Wednesday's hearing at the Paris terror trial was devoted to the content of a computer found in a bin in Brussels. According to the Belgian police investigator who presented the evidence, it is clear that the November 2015 attacks were intended to strike other targets, including Schiphol Airport near the Dutch city of Amsterdam.
The computer in question was found by Brussels binmen in March 2016, the day after the suicide attacks in the Belgian capital.
The machine was dumped in a plastic bag near one of the hideouts used by the terrorists. Many of the crucial files had been deleted, others had been deliberately coded and were indecipherable. But the file index survived.
That index includes a file called "13 November", within which are five sub-files:
The first is named "French group" and contains a photo of the Bataclan concert venue. Related files include a virtual visit to the Bataclan, normally used by sound and lighting engineers in the technical planning of events.
Then there is "Iraqi group," believed by the police to refer to the Stade de France attackers, of whom two were from Iraq. A separate file contains dozens of photos and diagrams of the sports venue.
The third sub-file, "Omar group," may refer to the terrace killers, led by the Paris attacks coordinator, Abdelhamid Abaaoud, whose Islamic State identity was Abou Omar.
The fourth is named "Métro group"
And the fifth sub-filed is entitled "Schiphol group".
If the first three suppositions are supported by the events of the night of 13 November 2015, the Métro and Schiphol elements remain unexplained.
Did the arrest of suspected terrorists, Adel Haddadi and Muhammed Usman, on their way back from Syria, force a last-minute change of plan?
Why did the co-accused, Osama Krayem and Sofien Ayari, travel by bus from Brussels to Amsterdam on the day of the Paris attacks, using false identities and buying one-way tickets?
Not for the first time in this epic process, one is torn between admiration for the amount of detailed evidence recovered by the police, and frustration that so many crucial questions remain unanswered.
The trial continues.
