The EU or European Union is an economic and political union of Europe. Ariane designed Austerlitz class was a proposed class of Tau'ri spaceship during the period Atlantis had returned to Earth. Construction was halted in the class because of financial problems, however, and so remained on the drawing board. (SGA: "Legacy: Homecoming")
Work resumed sometime after Atlantis back to Pegasus galaxy one, but only a single hull in this class was set by the EU who would use it when they are finished. (SGA: "The Furies")