in the fit. The resulting PDFs are called ZEUS-EW.

The PDG14 [@PDG14] value $M_Z=91.1876$GeV was used throughout the analysis. The PDG14 on-shell value of $\sin^2\theta_W=0.22333$ [@PDG14] and the corresponding SM couplings of the $Z$ boson to $u$- and $d$-type quarks were used unless these quantities were free parameters in the fits. The vector couplings of the $Z$ boson to electrons were calculated with the PDG14 on-shell value of $\sin^2\theta_W$ and kept fixed throughout the analysis unless $\sin^2\theta_W$ was a free parameter. In that case, all couplings of the $Z$ were recalculated according to the SM formulas. The PDG14 value of $M_W=80.385$GeV was used unless $M_W$ was a free parameter. The PDG14 value of $G_F = 1.1663787 \cdot 10^{-5}$GeV$^{-2}$ was used unless $M_W$ or $\sin^2\theta_W$ were free parameters in the fit, see Eq. \[eqn:GF\].

Only data with $Q^2 \ge 3.5$GeV$^2$ were considered in the analysis. This gives 2942 cross-section points, of which 501 (360 NC and 141 CC) are cross sections measured by ZEUS for polarised beams. Detailed information on these ZEUS data on cross sections for polarised beams are given[^3] in Table \[tab:pol\]. The number of cross sections used as input to the analysis presented here is much larger than 