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_DATA_MAP is used to mark the beginning and end of dialog data exchange (DDX) function calls in a dialog class’s DoDataExchange member function:
//{{AFX_DATA_MAP(classname)
...
//}}AFX_DATA_MAP
For more information, see AFX_DATA_INIT and AFX_DATA.