Kim et al classification system deals with:

According to Kim et al Classification; there are 5 types Type I incomplete isthmus between 2 canals. Type II well defined, complete isthmus between 2 canals. Type III very short but complete isthmus between 2 canals. Type IV 3 or more canals with the complete or incomplete isthmus. Type V 3 or more canals without any visible connection.