Setting the Property Set Class Identifier

The IPropertyStorage::SetClass method sets both the CLSID of the storage object and the class tag value stored in the COM property set. This occurs when invoked on a nonsimple property storage stored in a structured storage object.

This provides consistency and uniformity which creates better interaction with some tools. A property storage object is nonsimple if it is created by calling IPropertySetStorage::Create with the PROPSETFLAG_NONSIMPLE flag set.

The CLSID of the storage object is set with a call to IStorage::SetClass.