Inac ja v delphi nerobim, mne sa zda normalnejsie C++, tam su tusim 3typy dedenia a myslim ze rozumne zadefinovane:
You can derive classes using any of the three access specifiers:
* In a public base class, public and protected members of the base class remain public and protected members of the derived class.
* In a protected base class, public and protected members of the base class are protected members of the derived class.
* In a private base class, public and protected members of the base class become private members of the derived class.

P.S. Sa mi aj zda ze v delphi sa aj nejako miesa "visibility" s "accessibility", co su pre mna (C++ zalozeneho) dve totalne odlisne veci. No ale kazdemu podla jeho chuti...