Handling Commands in the Document
Your document class may also handle certain commands generated by menu items, toolbar buttons, or accelerator keys. By default, CDocument
handles the Save and Save As commands on the File menu, using serialization. Other commands that affect the data may also be handled by member functions of your document. For example, in the Scribble program, class CScribDoc
provides a handler for the Edit Clear All command, which deletes all of the data currently stored in the document. Documents can have message maps, but unlike views, documents cannot handle standard Windows messages — only WM_COMMAND messages, or "commands."