This document specifies Type S1 and Type S2 software measurement standards for verifying the software of measuring instruments. It also specifies the surface data file (SDF) format of Type S1 software measurement standards for the calibration of instruments for the measurement of surface texture by the areal method as defined in the areal surface texture chain of standards, chain link G. The SDF format is suitable for areal topography measurement data extracted with an orthogonal grid (see ISO 14406:2010, 5.2) and equidistant sampling intervals, regardless of the measurement principle. NOTE Throughout this document, the term softgauge is used as a substitute for software measurement standard Type S1 .