# OLE 1 Compatibility Subkeys

To handle two-way compatibility, the OLE 2 compatibility layer creates OLE 2-style entries for OLE 1 classes it discovers and places them under the CLSID key. When installing an OLE 2 object application on a system that contains an OLE 1 version of the same application, it might be necessary to add “ AutoConvertTo” or “ TreatAs” subkeys to the original OLE 1 application portion of the registry. For more information, see “ When the OLE 1 Version Is Overwritten,” later in this section.