Please do not include any trademark acknowledgements in GNU software packages or documentation.
Trademark acknowledgements are the statements that such-and-such is a trademark of so-and-so. The GNU Project has no objection to the basic idea of trademarks, but these acknowledgements feel like kowtowing, and there is no legal requirement for them, so we don’t use them.
What is legally required, as regards other people’s trademarks, is to avoid using them in ways which a reader might reasonably understand as naming or labeling our own programs or activities. For example, since “Objective C” is (or at least was) a trademark, we made sure to say that we provide a “compiler for the Objective C language” rather than an “Objective C compiler”. The latter would have been meant as a shorter way of saying the former, but it does not explicitly state the relationship, so it could be misinterpreted as using “Objective C” as a label for the compiler rather than for the language.
Please don’t use “win” as an abbreviation for Microsoft Windows in GNU software or documentation. In hacker terminology, calling something a “win” is a form of praise. If you wish to praise Microsoft Windows when speaking on your own, by all means do so, but not in GNU software. Usually we write the name “Windows” in full, but when brevity is very important (as in file names and sometimes symbol names), we abbreviate it to “w”. For instance, the files and functions in Emacs that deal with Windows start with ‘w32’.