There’s no road map for European authorities facing the prospect of a British exit from their 28-nation union -- by design.

Officials in Brussels are under orders not to commit any scenarios to paper to avoid alarmist leaks, according to a senior official from one European government tasked with making preparations.

Given the potential political and financial shockwaves surrounding a Brexit vote, it’s not clear a map would do much good. Global markets are already sputtering as anxiety mounts about the impact on the world economy. EU President Donald Tusk goes so far as to say that it could spell the end of “western political civilization itself.”

Brexit Watch:

The pound, the polls and the probability of Brexit Chaos awaits beseiged Cameron no matter what the result
Tusk’s exaggeration highlights the task in self-preservation awaiting European officials as they confront the potential departure of a country from the EU -- something that was inconceivable when the union was established. The mechanism for an exit was only written into law in 2009.

The First 24 Hours

Before dawn on June 24, if an exit vote becomes clear, the EU’s top brass from Berlin to Brussels will be forced into damage control. In echoes of the Greek debt crisis, euro-area finance ministers may hold an emergency meeting as soon as that evening. Wild swings in the pound, more aggressive interventions by the Swiss National Bank and a ratcheting up of global instability rank as likely market reactions.

Currency markets haven’t priced in the U.K.’s exit from the EU, so if it happens, “a crash is pretty likely,” Lothar Mentel, chief executive officer of Tatton Investment Management in London, said on Bloomberg Television. “We would have to brace ourselves for quite a rough awakening on that Friday.”

The political fallout may be even more fraught. Europe’s traditional counterweights, France and Germany, whose enmity the EU was set up to banish, will seek to gain some of the initiative. They are planning a response as early as June 24 that could include a commitment to deeper euro-area integration as well as a declaration that the EU dream remains alive, according to three people familiar with the plans.

“The European Union will need to have a credible strategy,” said Guntram Wolff, of the Brussels-based policy group Bruegel. “To avoid a gradual disintegration of the EU, political leaders will need to strengthen the attractiveness of the EU and especially the Franco-German alliance.”