This discussion should be instructive for the serious student. For learning the language, it is not necessary and may be skipped. An example of an ablaut sequence in English is ring, rang, rung . All 173 irregular verbs follow an ablaut sequence. The applicable sequence is a specific one for the particular stem master vowel.
Some long vowels follow a sequence different from that of the corresponding short-vowel sequence.
The long vowels are shown underlined in the following table. They may be spelled ah, eh, ie, ih, oh, or uh . The size of the ablaut classes is listed in the column Anzahl der Verben , which is the number of verbs in that sequence. In addition to an ablaut sequence, some of the irregular verbs change the last consonant of the word stem, which is called Konsonantenwechsel . More precisely, it is the consonant immediately following the stem master vowel that changes.