midl /newtlb <other-options> filename
midl /newtlb filename.idl
midl filename.idl
This is the default setting for choosing a type library format. 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. Thus, if the new OLEAUT32.DLL is present, this switch does nothing. If the new OLEAUT32.DLL is not present, specifying this switch in the MIDL command line will generate an error.
General MIDL Command-line Syntax, /oldtlb