Relation between RASS blind fluxes and SZ fluxes, Y₅₀₀, for single systems confirmed with XMM-Newton (all validation observations). The RASS flux is the unabsorbed flux computed in the [0.1−2.4] keV band and measured in a 5′ aperture centred on the Planck position. The points are colour-coded as a function of redshift. Squares are candidates associated with a FSC source while diamonds are candidates associated with a BSC source.