GDL scripts define an Archicad library part in its main roles, these are 3D model, 3D model projected to section/elevation or to 2D plan, 2D plan view, user interface display and behaviour and listing quantities.
All versions of the Archicad contain their own default libraries, also objects like furniture, windows, doors, trees, people, cars, construction elements, etc.
There are several commercial websites for selling high-detailed intelligent parametric objects, which are perhaps better and more variable than the default libraries, for example there are a lot of environmental objects like plants, people or garden elements, which are not included in the original software.
In 2D and 3D in GDL, all the model elements are linked to a local right-handed coordinate system.
Every movement, rotation or stretching of the coordinate system is called a transformation.