这里是什么意思?

Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)
Dim pos As Long, lc As Long
Dim Line As Integer, CharPos As Integer

x = x / Screen.TwipsPerPixelX
y = y / Screen.TwipsPerPixelY
pos = x + y * 65536
lc = SendMessage(Text1.hwnd, EM_CHARFROMPOS, 0, ByVal pos)
Debug.Print lc
Line = lc \ 65536 '这里是什么意思?
CharPos = lc Mod 65536 '这里是什么意思?

MsgBox "第几行 = " & Line & vbCrLf & "第几个字符= " & CharPos
End Sub