There is evidence that Danian underwent i-mutation is some circumstances, notably a change of [a] > [e] in the names Gochressiel from hrassa “precipice” (Ety/KHARÁS) and Denethor from ᴹ✶Ndanithārō (Ety/DAN, LR/188), as well as [u] > [y] in the plural yrc of urc (Ety/ÓROK). These same changes also occurred in Old English and Old Norse, the real-world inspirations of Ossiriandic and East Danian (ref/@@@). It is likely i-mutation occurred for other vowels, but there is not enough evidence to determine what they were.