In MDT 2008, we had various functions in the ZTIUtility.vbs script that could be used in CustomSettings.ini – not that we really intended for that to be the case, but because the “Gather” process can call any global VBScript function, so it just works.
In MDT 2010, we rearranged the logic in ZTIUtility.vbs into different classes, just to make the script more modular and maintainable. But as a result, some of those global functions were no longer global, so anyone trying to use them wouldn’t be able to any more.
Michael Murgolo noticed this, as he was using the ConvertBooleanToString function in the blog posting at http://blogs.technet.com/b/deploymentguys/archive/2010/02/15/using-convertbooleantostring-with-ztigather-wsf-in-mdt-2010.aspx. To fix this issue (and to avoid anyone needing to implement a workaround) we added logic in MDT 2010 Update 1 to make the function global again.