Sub MenuSelect()
Dim ScreenNo

If (SmartTags("FAST\MainMenu\ScreenNo") = 100) Or  (SmartTags("FAST\MainMenu\ScreenNo") = 200) Or  (SmartTags("FAST\MainMenu\ScreenNo") = 300) Then
 If (SmartTags("FAST\MainMenu\ScreenNo_Last_user_1") <> 0) And  (SmartTags("FAST\MainMenu\ScreenNo_Last_user_1") <> 1) Then
  SetTag ScreenNo, SmartTags("FAST\MainMenu\ScreenNo_Last_user_1")
    SetTag "FAST\MainMenu\ScreenNo_Last_user_1", SmartTags("FAST\MainMenu\ScreenNo_Last_user_0")
    SetTag "FAST\MainMenu\ScreenNo_Last_user_0", ScreenNo
   Else
       SetTag ScreenNo, SmartTags("FAST\MainMenu\ScreenNo_Last_user_0")
 End If
Else  'FROM ANY SCREEN
 If SmartTags("FAST\MainMenu\ScreenNo") <> SmartTags("FAST\MainMenu\ScreenNo_Last_user_0") Then
    SetTag "FAST\MainMenu\ScreenNo_Last_user_1", SmartTags("FAST\MainMenu\ScreenNo_Last_user_0")
    SetTag "FAST\MainMenu\ScreenNo_Last_user_0", SmartTags("FAST\MainMenu\ScreenNo")
   End If
 If (SmartTags("FAST\MainMenu\Menue_Last") = 100) Or  (SmartTags("FAST\MainMenu\Menue_Last") = 200) Or  (SmartTags("FAST\MainMenu\Menue_Last") = 300) Then
     SetTag ScreenNo, SmartTags("FAST\MainMenu\Menue_Last")
 Else
  SetTag ScreenNo, 100
 End If

  
End If
  
ChangeScreen ScreenNo, 0
End Sub

请问各位大侠,标红的语句是什么意思呢?