vocalic ( > , but > ) or, regardless of syllable weight, if followed by consonantal ( > ). The rule is not perfect, as some light syllables were still umlauted: > , > . In Old Norse, if the following syllable contains a remaining Proto-Norse . For example, the root of the dative singular of u-stems are i-mutated as the desinence contains a Proto-Norse , but the dative singular of a-stems is not, as their desinence stems from Proto-Norse . I-mutation is not phonological if the vowel of a long syllable is i-mutated by a syncopated i. I-mutation does not occur in short syllables. See also Germanic a-mutation I-mutation Indo-European ablaut Umlaut (disambiguation) Umlaut (diacritic) References Bibliography Malmkjær, Kirsten (Ed.) (2002). The linguistics encyclopedia (2nd ed.). London: Routledge, Taylor & Francis Group. . Campbell, Lyle (2004). Historical Linguistics: An Introduction (2nd ed.). Edinburgh University Press. Cercignani, Fausto, Early "Umlaut" Phenomena in the Germanic Languages, in «Language», 56/1, 1980, pp. 126–136. Cercignani, Fausto, Alleged Gothic Umlauts, in «Indogermanische Forschungen», 85, 1980, pp. 207–213. Cercignani, Fausto, The development of the Old High German umlauted vowels and the reflex of New High German /ɛ:/ in Present Standard German, in «Linguistik online», 113/1, 2022, pp. 45–57. . Cercignani, Fausto, On the Germanic and Old High German distance assimilation changes, in «Linguistik online», 116/4, 2022, pp. 41–59. . Assimilation (linguistics) Vowel shifts German language Linguistic morphology Germanic language histories Indo-European linguistics Germanic languages Germanic philology Sound laws