The /oldtlb switch directs the MIDL compiler to generate an old-format type library.
midl /oldtlb <other-options> filename
midl /oldtlb filename.idl
midl /oldtlb myoldodl.odl
The /oldtlb switch determines the format of MIDL-generated type libraries.
Effective with Windows NT 4.0, there is a new version of OLEAUT32.DLL that supports a richer format for 32-bit type libraries. MIDL looks for this DLL on the build machine; if the new version is present, MIDL generates a new-format type library. Otherwise, it generates an old-format type library. The /oldtlb switch overrides this default and directs the MIDL compiler to generate old-format type libraries even if the newer version of OLEAUT32.DLL is present.
General MIDL Command-line Syntax, /newtlb