Abdymok provides a copy of the Terms of Reference for the Joint Ukrainian/Russian and EU Monitors here (letter with signatures) and here (actual text).
The letter says that the terms of reference are "for resuming the natural gas deliveries from the Russian Federation through Ukraine to the European Union".
It seems that apart from a start date (from immediate effect) there is no finish date. Evidently nobody thought this would drag on and as soon as the monitors began monitoring everything would become clear and gas would flow.
Not so, as it turns out. So how long will the monitors stay there? It doesn't say. Their costs are paid for by the countries sending them. The Terms of Reference guarantee the right of access on the territory of Russia and Ukraine to the metering stations, and the right of access to data.
How long will this go on? Will it become an annual event? If the Ukrainian gas network gets sold to the Russians will it still stand, when the next dispute come up?
Is this really a way to ensure security of gas supply to the EU?
Now the EU is telling EU gas companies to sue Russia. It will be an interesting question to see in which jurisdiction they need to sue. With both Russia and Ukraine strapped for cash, will this help? Or will EU companies accept the Ukrainian gas network as compensation? Now that would really put the cat among the pigeons.
But it might be a reasonable solution for the EU. Then Russia and Ukraine could have their annual battle about prices and the EU could share the gas as necessary.