The /ms_union switch controls the NDR alignment of nonencapsulated unions.
This switch has no parameters.
The MIDL compiler mirrors the behavior of the OSF-DCE IDL compiler for nonencapsulated unions. However, because earlier versions of the MIDL compiler did not do so, the /ms_union switch provides compatibility with interfaces built on previous versions of the MIDL compiler.
The ms_union feature can be used as a command-line switch (/ms_union), an IDL interface attribute, or as an IDL-type attribute.
midl /ms_union file.idl