IMPLEMENT_DYNCREATE(CMainFrame, CFrameWnd)

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
    ON_COMMAND_EX(CG_ID_VIEW_COLORDLGBAR, OnBarCheck)
    ON_UPDATE_COMMAND_UI(CG_ID_VIEW_COLORDLGBAR, OnUpdateControlBarMenu)
    //{{AFX_MSG_MAP(CMainFrame)
    ON_WM_CREATE()
    ON_UPDATE_COMMAND_UI(ID_EDIT_UNDO, OnUpdateEditUndo)
    ON_UPDATE_COMMAND_UI(ID_EDIT_REDO, OnUpdateEditRedo)
    ON_COMMAND(ID_EDIT_UNDO, OnEditUndo)
    ON_COMMAND(ID_EDIT_REDO, OnEditRedo)
    ON_COMMAND(ID_FILE_NEW, OnFileNew)
    //}}AFX_MSG_MAP
    ON_COMMAND_RANGE(ID_TOOLS_FREEDRAW, ID_TOOLS_SPRAY, OnToolBarCommandCheck)
    ON_UPDATE_COMMAND_UI_RANGE(ID_TOOLS_FREEDRAW, ID_TOOLS_SPRAY, OnUpdateToolBarCheck)
END_MESSAGE_MAP()


여기서 대문자로 구성되있는것은 머라고 불리는지 어떨때 대문자로 쓰이는지좀 알려주세여