CmdTarget is the base class for the message-map architecture. A message map routes commands or messages to the member functions you write to handle them. (A command is a message from a menu item, command button, or accelerator key.)
Key framework classes derived from CmdTarget include Window, ObjectCmdTarget. If you intend for a new class to handle messages, derive the class from one of these CmdTarget-derived classes. You will rarely derive a class from CmdTarget directly.