The Mu+ (6.9 GeV) is identified as minimum ionizing in the HPC and HAB and has a hit associated in the outer plane of the MUF.
The Mu- (8.5 GeV) appears as minimum ionizing in the HPC and has hits associated in both planes of the MUF.
The peculiarity of this event is that both muons have a large transverse momentum to the jets and is thus unlikely to be due to the semi-leptonic decay of a quark. They also form a system with large invariant mass (7.4 GeV) and large angles with the beam (40 degree) and with the quark jets (85 degree). They are therefore unlikely if interpreted as radiative production of a muon pair.
Ref : this event was presented by J.E.Augustin in the LEPC Meeting of 13 feb 1990 (see note DELPHI 90-3 GEN-103) as a candidate four lepton final state with heavy bremmstrahlung with a probability of about 10%.