I just checked in a doc, using <trademark class="trade"> for LibreOffice, and someone very quickly changed it from trade to copyright.
If you look at the bottom of the page www.libreoffice.com, they have "LibreOffice" and "The Document Foundation" are registered trademarks which is why I explicitly used trade instead of copyright, although perhaps registered would have been better. The code and system is probably copyright, but the name is trademarked. I think the OO reference (for which I used copyright) is probably also incorrect, but I haven't changed it since I haven't found a good reference. If you look at the wikipedia pages for them, I don't see (C) (R) or TM used within the text, but in the graphic at the right of each page, oo.org has a TM, and LibreOffice seems to have a (R). Is there a KDE preference or standard for this type or reference? I don't see anything in any of the entity defining files. Thanks for any pointers. Jack