D4i stands for DALI for intra-luminaire, basically DALI integratedrith into the light fixture. It is like the upgraded version of DALI-2, it's got three extra features compared to regular DALI-2 devices: 1) D4i drivers come with integrated bus power, making it a breeze to power up controllers and sensors on the lamp, simplifying the wiring; 2) It can strore and report a ton of data lamp asset infomation,energy consumption,diagnostics and maintenance data, helps property owners meet energy-related regulations; 3) D4i supports plug-and-paly sensors,like zhaga sensor, makes it super easy for light to connect to wireless network.