The Ligo Library comprises two sets of classes. The first set implement primitives. (see in code/nel/include/nel/ligo and code/nel/src/ligo). A primitive is a set of properties usually associated to a geographical area (CPrimZone) and can be placed by a level designer. Primitives are stored in an XML file, the structure of which is described in a primitive class XML file.
The second set of classes is related to NeL Ligoscape. They are all located in code/nel/src/ligo. Some tools can be found in code/nel/tools/3d/ligo.