This International Standard specifies the properties of heat treated screws with a tapping screw thread in accordance with ISO 1478, and which are designed with a drilling point which automatically drills the core hole for the screw during assembly. Such screws then automatically form the mating screw thread, either in a non-cutting or in a cutting operation, with the aid of the threaded portion of the screw adjoining the drilling point. The purpose of this International Standard is to ensure that the screws are able to drill their core hole and form their mating screw thread without becoming distorted or fracturing in the process, provided that no overstressing has occurred. Consequently the following characteristics are regarded as representing the most important aspects for the assessment of the mechanical and operational characteristics of a drilling screw: ¾ surface hardness; ¾ capability of core hole drilling and forming of the mating female screw thread; ¾ torsional strength