From Forum Nokia Wiki

M classes define abstract protocols, or interfaces. Concrete implementations of an interface defined by an M class are provided by derived protocol provider classes.

M classes have the following restrictions:

• They should contain no member data
• They should not contain constructors or destructors, or overloaded operators such as =.

M classes often contain pure virtual functions that define a fully abstract interface. Some M classes implement some or all member functions, though within the restrictions given above.

M classes are the only use of multiple inheritance in Symbian OS.

External Links

• M Classes