groove interfit which facilitates installation by placing the weight of an upper panel on an underlying lower panel instead of requiring an installer to hold the panel in place against gravity mounting nails are used in combination with the tongue and groove interfit to positively lock the tongue of one panel into the groove of the underlying panel nail placement is controlled by the relative placement of nail slots and hammer abutment surfaces formed on each panel because the panels must be pivoted in place and held in place by the overhanging siding nails it is virtually impossible for the installer to make a mistake that results in an upper siding panel coming loose from the siding panel below application_number US 50033495 A description a better appreciation of the present invention can be realized from a brief review of a siding panel construction arranged according to the prior art as shown in fig1 and 2 prior vinyl siding constructions typically include a panel 10 having a top nailing or mounting strip 12 formed with slots 14 for receiving mounting nails 16 below the mounting strip 12 a somewhat n shaped sinuous ridge 18 defines a downwardly facing groove 20 for receiving a mounting lip 22 formed.