https://bugs.winehq.org/show_bug.cgi?id=57476
--- Comment #2 from Thomas Linder Puls thomas_linder_puls@hotmail.com --- (If Windows SDK provided an idl file I would never have found yours).
I use the file to create a type library dwrite.tlb with Microsofts IDL compiler. Which is unfortunately also not in the SDK.
For my programming language (Visual Prolog) I have a tool that can read such type libraries and generate code for using such COM objects. And for the tool to generate that code correctly it is important to know whether an argument is input or output.
I am fully aware that C++ is completely indifferent to such things and leaves all the handling to the programmer.
I will see if I can figure out to make a merge request but I have tried that before and at that time it wouldn't accept a hotmail email account. And that stopped me.