Remarks
ClassWizard and AppWizard insert specially formatted comment delimiters in your source code files to mark the places in your files that ClassWizard can write to. AFX_EVENT_MAP is used to mark the beginning and end of OLE events in a class’s implementation (.CPP) file:
//{{AFX_EVENT_MAP(classname)
...
//}}AFX_EVENT_MAP
For more information, see AFX_EVENT.