Config += no_batch Where is the documentation for this option.

When my project's qmake runs (qtcreator 4.2.0) I got this message:

Automatically turning off nmake's inference rules. (CONFIG += no_batch)

Couple of questions:
Why does it references "nmake"? Is it because I am using Microsoft compiler?

I can't find any reference documentation on no_batch option. Moreover, google search brought me to the page where another option, object_parallel_to_source, is also mentioned.

Perhaps someone knows where I can read about them? QMake Manual index has nothing, or I am missing something.

Thanks.