Code for "Undo"

what is the code for undo???

Declare Function SendMessage Lib "User" (ByVal hWnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, lParam As Any) As Long
Global Const WM_USER = &h400
Global Const EM_UNDO = WM_USER + 23

sub command1_click
UndoResult = SendMessage(myControl.hWnd, EM_UNDO, 0, 0)
end sub