Hi Tomas,
The purpose of this forum is to work with third-party developers who are consuming Microsoft's protocol specifications at https://docs.microsoft.com/en-us/openspecs/main/ms-openspeclp/3589baea-5b22-48f2-9d43-f5bea4960ddb. This library
does include some file formats, but they are mostly on-the-wire network protocol technical documents.
It is not likely that your question is covered under that umbrella. But, to be sure would you please explain more what "Big Obj file" format you are referencing. We're a little unsure. Is it the .OBJ file format, for instance,
that a compiler would emit or something else. If we knew more about this topic we might be more useful in helping you find a venue where you can get the help you need.
Bryan S. Burgin Senior Escalation Engineer Microsoft Protocol Open Specifications Team