As the first step of border arbitration, a five-member arbitral tribunal must be established in a month. Within 15 days the two countries need to choose three members from a list of respected international-law experts compiled by the European Commission and within a month each their own member.

While Slovenia and Croatia have already appointed their arbiters, Jernej Sekolec and Budimir Vukas respectively, choosing the three common members by 24 December may prove more problematic.

Although the composition of the tribunal should in theory be known by Christmas, the two countries are unlikely to come to an agreement on the names, as the European Commission's list will not be revealed before the Croatia signs the Accession Treaty.

Diplomatic sources therefore find it more likely that the three arbiters will be picked by the president of the International Court of Justice (ICJ), a contingency provided in the Arbitration Agreement.

However, the accord does not set a deadline for this backup plan and ICJ President Hisashi Owada's term at the helm of the court ends in February.

The two countries have one month from the start of proceedings (presumably until 9 January 2012) to precisely specify the subject-matter of the dispute.

However, this is also unlikely since Slovenia and Croatia have failed to do this so far, and the exact scope of the maritime and territorial disputes and claims will probably be determined by the arbitral tribunal based on the memorials in which the two sides will present their arguments.

Both parties must submit the memorials within a year of the signing of the Accession Treaty, and the countries will probably take all the time available for preparing the documents, according to the Slovenian Foreign Ministry.

In general, the agreement already stipulates that the tribunal shall determine the "course of the maritime and land boundary between" the two countries, "Slovenia's junction to the High Sea" and the "regime for the use of the relevant maritime areas".

Upon receiving the memorials from Slovenia and Croatia, the tribunal sets the deadline for commenting on the memorial of the other party, whereupon the tribunal may seek expert advice and organise oral hearings.

The Brussels-based tribunal will also have a secretariat, which is to be aided by the European Commission. Each party is to cover half of the total costs, currently estimated at around EUR 10m.

The tribunal is to conduct the proceedings "according to the Permanent Court of Arbitration Optional Rules for Arbitrating Disputes between Two States" and reach a final decision "expeditiously".

The decision of the tribunal - with an explanation of the reasons on which it is based but without a dissenting opinion or possibility of appeal - is expected to take at least a year and a half, but more probably two years.

Details on the preparations in the two countries are not available, as both held general elections on Sunday. But both the likely new Slovenian prime minister, Zoran Jankovic, and the probable new Croatian foreign minister, Vesna Pusic, have expressed very positive opinions about the Arbitration Agreement.

The Arbitration Agreement was signed in Stockholm, Sweden, on 4 November 2009 under the auspices of the EU after Slovenia stopped Croatia's progress in its EU accession talks in a number of chapters in 2008, demanding that Croatia withdraw all the documents it had submitted during the course of the talks that may prejudge the disputed parts of the border.