I accidentally stumbled upon this keyword when I was programming. The keyword is clearly undocumented, although I was surprised that a compiler suggested that it must be specifically used as a last input parameter in a function or a method when I tried to declare a variable of this 'type'. When put in a function/method, it is considered '' for some reason. Having a variable argument support must be really nice... Disclaimer: I am using TwinCAT 4024.12, but for this type of question I have better...