This standard provides data and guidance for the design, manufacture, and inspection of straight, non-helical, cylindrical involute splines. It establishes a specification based on the metric module within the range 0.25-10 inclusive, relating to nominal pressure angles of 30 deg, 37.5 deg, and 45 deg. For computer programming, the term “37.5 deg” has been adopted instead of “37 deg, 30 min”. Limiting dimensions, variations, and manufacturing tolerances and their effect on the fit between connecting co-axial spline elements, are defined and tabulated. Linear dimensions are expressed in millimeters and micrometers. Angular dimensions are expressed in degrees and decimal degrees.