This event was the first ever of its type to occur in an electron - positron collider such as LEP in CERN. From the new W⁺W^- pair produced by the electron - positron annihilation, two quark - antiquark pairs were formed, each of which decayed straight away into a jet consisting of many different particles.

Notes for experts: The two pairs of back-to-back jets have masses consistent with 80 GeV/c². The first W decays into the red and the green jets, directed into the barrel of the detector. The second W decays into the yellow and the blue jets which go into the DELPHI endcaps. This event was the first W⁺W^- event recorded at an e⁺e^- collider.