7.4.1 Introduction

We produce a list of confirmed all-sky RR Lyrae and Cepheid stars cleaned from contaminating objects and other types of variables falling into the same period domain. For all stars we provide a number of attributes (with related errors) to be published in the second Gaia Data Release among which, specifically: period, peak-to-peak amplitudes, mean magnitudes and epoch of maximum light in $G$, $G_{\mathrm{BP}}$, $G_{\mathrm{RP}}$ bands (when $G_{\mathrm{BP}}$ and $G_{\mathrm{RP}}$ are available) as well as Fourier parameters from the $G$-band light curves. Additionally, for RR Lyrae stars for which the ${\varphi }_{31}$ Fourier parameter is available we provide a metallicity ([Fe/H]) estimate and, for RRab types we also publish an estimate of the interstellar absorption in the $G$-band. Also, for Cepheid stars with period shorter than about 6 days we provide an estimate of metallicity ([Fe/H]).