The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.
The latest version of this topic can be found at TN049: MFC-OLE MBCS to Unicode Translation Layer (MFCANS32).
This note originally described how MFCANS32.DLL provides ANSI interfaces in the primarily Unicode world of 32-bit OLE. This DLL is no longer used by MFC.