  We use cosmic microwave background (CMB) and large-scale structure data to
constrain cosmological models where the primordial perturbations have both an
adiabatic and a cold dark matter (CDM) isocurvature component. We allow for a
possible correlation between the adiabatic and isocurvature modes, and for
different spectral indices for the power in each mode and for their
correlation. We do a likelihood analysis with 11 independent parameters. We
discuss the effect of choosing the pivot scale for the definition of amplitude
parameters. The upper limit for the isocurvature fraction is 18% around a pivot
scale k = 0.01 Mpc^{-1}. For smaller pivot wavenumbers the limit stays about
the same. For larger pivot wavenumbers, very large values of the isocurvature
spectral index are favored, which makes the analysis problematic, but larger
isocurvature fractions seem to be allowed. For large isocurvature spectral
indices n_iso > 2 a positive correlation between the adiabatic and isocurvature
mode is favored, and for n_iso < 2 a negative correlation is favored. The upper
limit to the nonadiabatic contribution to the CMB temperature variance is 7.5%.
Of the standard cosmological parameters, determination of the CDM density
$\omega_c$ and the sound horizon angle $\theta$ (or the Hubble constant $H_0$)
are affected most by a possible presence of a correlated isocurvature
contribution. The baryon density $\omega_b$ nearly retains its ``adiabatic
value''.
