Looking an example source code wasn't enough, and I couldn't find any official documentation about theKbdLayerDescriptorsymbol. So I have still some questions about it :

• What is the purpose of the ligature table, or more precisely how does it works. Is it for writing pre‑composed characters ? If not, does it means automatically insert the ZERO WIDTH JOINER character, or it simply write several characters without ligature ?
• Is is possible to define three or more shift states with keys of the numeric pad ?
• I saw theKBD_TYPEneed to be defined. What are the purpose of each integer values ?
• Is it possible to use Unicode values larger than 16 bits like the mathematical𝚤 ?
• I saw keyboards layout use[HKLM\SYSTEM\CurrentControlSet\Control\Keyboard Layout\DosKeybCodes]and[HKLM\SYSTEM\CurrentControlSet\Control\Keyboard Layouts]but it seems it is not the only registry keys that need to be completed in order to register a system wide keyboard. So what are the required registry keys for installing a system wide keyboard layout ?