Quote from Wikipedia - "A software development kit (SDK or "devkit") is typically a set of development tools that allows for the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar platform."
See for example on forum
and also on TurboCAD forum
To use this scripts you should have installed Microsoft.NET frameworks This examples are in Visual Basic.
For DoubleCAD Pro we can write scripts in Ruby, too. There is currently no documentation, and it is only the beginning, but as you probably noticed DuobleCAD growing very rapidly and change occurs very quickly, unfortunately, sometimes at the expense of bugs.
In DoubleCAD Pro you can create PPM too - Parametric Parts , with which you can create a script, where by entering a few variables, for example you can change the size of inserted windows, doors, furniture ... or automate some calculations (see http://forums.doublecad.com/index.php?topic=648.0
and others in this thread).