This Prestandard, together with prEN1046:2000 and EN1610:1997, provides a material-specific set of guidelines for the installation of piping systems made of unplasticized poly(vinyl chloride) (PVC-U) in the field of non-pressure underground drainage and sewerage - outside the building structure (application area code " U" ) - both buried in ground within the building structure (application area code " D" ) and outside the building. This is reflected in the marking of products by " U" and " UD" .