/IDLOUT (Name MIDL Output Files)
The /IDLOUT option specifies the name and extension of the .idl file.
The MIDL compiler is called by the Visual C++ linker when linking projects that have the module attribute.
/IDLOUT also specifies the file names of the other output files associated with the MIDL compiler:
filename is the parameter that you pass to /IDLOUT. If /TLBOUT is specified, the .tlb file will get its name from /TLBOUT filename.
If you specify neither /IDLOUT nor /TLBOUT, the linker will create vc70.tlb, vc70.idl, vc70_p.c, vc70_i.c, and vc70.h.
To set this linker option in the Visual Studio development environment
Open the project's Property Pages dialog box. For details, see Setting Visual C++ Project Properties.
Click the Linker folder.
Click the Embedded IDL property page.
Modify the Merge IDL Base File Name property.