Due to numerous requests, we put together this simple decoder to help identify the basic features of this common type of German spline. DIN 5480 can be confusing to those familiar with ANSI and ISO involute splines as it is based around the concept of a “Reference Diameter” with limited outcomes rather than a linear set of uniform ratios covering all tooth and Module combinations. This TechBit addresses some of those common misunderstandings and describes the basics of DIN 5480.