"Combination covariance matrix" of "Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at $\sqrt{s}= 7$ and 8 TeV"

Full covariance matrix including all systematic uncertainties expressed as nuisance parameters.
With the exception of the cross section parameters, all parameters were normalised to 1 before the fit.
Therefore, the diagonal elements represent the constraint in quadrature.