The file names for pages defined with the \page command will not contain any non-ascii-printable character in their file names. That's fine considering the behavior of various filesystems, etc. However, QDoc doesn't warn if it encounters such a page. Rather, it drops the non-conforming/illegal characters. Page names that mix ascii and non-latin characters are generated using solely their ascii-printable part(s), pages that contain no ascii-printable characters at all aren't generated at all.