Run-time method determination extends the power of both data abstraction and inheritance. Object-oriented programming languages allow programs to work on objects without knowing the exact type of the object. The method to be called to answer a function call must, therefore, be determined at run time. This process is called jielding a message. A simple mechanism that determines the method is to examine a class identifier hidden in each object and dispatch a method based on the object’s class. A message may cause the execution of more than one method: a method for LSOO may, for example, do some work, then call the message’s method defined by LS to complete the work.