Specifies whether or not an application uses a custom handler.
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
\InprocHandler32 = <handler.dll>
If A custom handler is not used, the entry should be set to COM32.DLL, as shown in the following example.
HKEY_-CLASSES_ROOT\CLSID\{00000402-0000-0000-C000-000000000046}
\InprocHandler = ole32.dll
If a container is searching the registry for an InprocHandler, the 16-bit version has priority with a 16-bit container, and the 32-bit version has priority with a 32-bit container.