The /h option is functionally equivalent to the /header option.
midl /h filename
Specifies a header file name that overrides the default header file name. File names can be explicitly quoted using double quotes (") to prevent the shell from interpreting special characters.
The /h switch specifies filename as the name for a header file that contains all the definitions contained in the IDL file, without the IDL syntax. This file can be used as a C or C++ header file.
midl /h tlibhead.h filename.idl
midl /h "midl.h" filename.idl