NaroCAD can work with BREP shapes right now (right now only to import) but rest of others operations will follow.
Which kind of format BREP? BREP stands from Boundary Representation and it is like Step format. Is a format implemented in OpenCascade and using the Import/Export application provided with OpenCascade you can convert any formats like: STEP or STL to BREP.
The imported shapes can be as complex as OpenCascade can store, still the shape as it is, at NaroCAD level it does not offer the high level attributes but only dumb geometry.
I would plan to finish today saving to BREP and save/load using Xml of Naro internal data.
So if you will create a shape in NaroCAD and you will want to import it to other CAD software, you may use BREP. If you will need some information attached to a specific shape, you may use Xml.