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_FIELD_MAP is used in MFC database applications to mark the beginning and end of record field exchange function calls in a recordset class’s DoFieldExchange member function:
//{{AFX_FIELD_MAP(classname)
...
//}}AFX_FIELD_MAP
For more information, see AFX_FIELD_INIT and AFX_FIELD.