Attachmate Refleciton Open Systems .waitfor metod

I'm working with automation of Attachmate Reflection Open System application. I wonder if there's any way to wait for all screen data to be loaded. Previously I was working with Reflection IBM application. I was using e.g. function: IbmScreen.WaitForText1, with arguments: timeout, text, row, column; So I was able to wait until specific text will appear in screen row and column.

Open System application has similar function: osCurrentScreen.WaitForString2, but only 2 arguments: text (string) and timeout (long). I do not understand how this function works. When I record macro, some wierd staff comes up, e.g.:

Dim osCurrentScreen As Screen
Dim osCurrentTerminal As Terminal
Dim returnValue As Integer



Const NEVER_TIME_OUT = 0

Dim CR As String    ' Chr(rcCR) = Chr(13) = Control-M
Dim SI As String    ' Chr(rcSI) = Chr(15) = Control-O
Dim ESC As String   ' Chr(rcESC) = Chr(27) = Control-[

Set osCurrentTerminal = ThisFrame.SelectedView.control
Set osCurrentScreen = osCurrentTerminal.Screen

CR = Chr(13)
SI = Chr(15)
ESC = Chr(27)

returnvalue = osCurrentScreen.WaitForString2("j" & SI & ESC & "[;;4m" & ESC & "[03;20H                ", timeout)

I can not understand what's this SI and ESC character means - I can not find any rule how is that macro code generated.

Is there any other option to wait for data to be fully loaded?