OBJECT-ORIENTED METRICS - A SURVEY
Michalis Xenos, D. Stavrinoudis, K. Zikouli, Dimitris Christodoulakis, Agiou Andreou · 2000
Data types) is the number of user-defined objects used as attributes in a class that are necessary to instantiate an object instance of the class [36]. NCM (Number of Class Methods in a class) measures the measures available in a class but not in its instances [37].