  We confront different models for medium modifications of the electromagnetic
correlation function to recent dimuon spectra from the NA60 collaboration for
central In-In collisions at the CERN-SPS. In the low-mass region (M \lesssim
1.0 GeV), we evaluate medium modifications of the spectral properties of \rho-,
\omega- and \phi-mesons. In the intermediate-mass region (M>1.0 GeV), we employ
schematic models for the mixing of vector and axialvector current correlators,
which provide a mechanism for chiral-symmetry restoration.
