The global standardising association Zhaga has published Book 20 that defines a smart interface between an indoor LED luminaire and a sensing/communication module. The module connects to the LED driver, and typically provides sensory inputs or enables communication between network components. This Book brings together complementary specifications from the Zhaga Consortium and the D4i specifications from the Digital Illumination Interface Alliance (DiiA). Zhaga Book 20 eases invest decisions for end-users, as luminaires can be adapted when needed with modules for different functions, like air quality sensing, presence detection or light levels controlling. The specification provides benefits to luminaire makers, when certified modules from multiple suppliers providing a wide range of different functions are available and it helps installers, as a certification on the interoperability of components exists. The new Zhaga-D4i certification is available for LED luminaires and LED control gear fulfilling the D4i requirements. Luminaires can now be certified by Dekraand Inertek, as the Zhaga accredited test centres. Zhaga-D4i certification of sensors and/or communication modules will become available later in 2020.