From reading this tutorial, the model is first welded throughout, and then split, with a splitting angle of 43 degrees. This will split the mode around the edges of the indentations, which are coloured black in the final image. The final model has a mixture of welded and unwelded vertices, and therefore a mixture of smooth and sharp (hard) edges, stemming from the 43 degree splitting angle. Whilst the final model has no additional facets, it does have additional vertices, compare to the fully welded version.