I see a lot of people asking for a way to Aim-Down-Sights by holding Right-Mouse-Button.
The default behavior of DayZ's ADS is to click RMB to Toggle it.
There appears to be no way to hold RMB to ADS, like in many other FPS games, without using third-party macro hardware/software.

The input user action UAADSToggle currently allows toggling in/out of ADS.
However if there was a separate input action introduced without a Toggle-mechanism, e.g. a new "UAADS" keybind, this could easily be simplified.