1. The alternation (ablaut) mostly involves vowels (change in vowel, vowel length, or nasality) and tone, but sometimes includes the suffixation of a final consonant.

Le phénomène d'alternance (ablaut) implique principalement les voyelles (changement de voyelle, de longueur de voyelle, ou de nasalité) et le ton, mais parfois concerne la suffixation d'une consonne finale.

2. For example, the word that appears as ktbu "they wrote" in Jeffrey Heath's Ablaut and Ambiguity: Phonology of a Moroccan Arabic Dialect appears as ketbu in Harrell's grammar.

For example, the word that appears as ktbu "they wrote" in Jeffrey Heath's Ablaut and Ambiguity: Phonology of a Moroccan Arabic Dialect appears as ketbu in Harrell's grammar. (en) Cet article est partiellement ou en totalité issu de l’article de Wikipédia en anglais intitulé « consonant cluster » (voir la liste des auteurs).

3. The generation of Indo-Europeanists active in the last third of the 20th century (such as Calvert Watkins, Jochem Schindler, and Helmut Rix) developed a better understanding of morphology and of ablaut in the wake of Kuryłowicz's 1956 Apophony in Indo-European, who in 1927 pointed out the existence of the Hittite consonant ḫ.

La génération d'indo-européanistes active dans le dernier tiers du XXe siècle (comme Calvert Watkins (en), Jochem Schindler (en) et Helmut Rix), a approfondi la compréhension de la morphologie et, dans la vague de L'apophonie en indo-européen de Kuryłowicz (1956), de l'alternance vocalique.