The vocalic contrasts displayed by figure 1 have been largely discussed in the literature as ablaut (or apophony) and the different vocalic value are usually referred to as ablaut grades.
While the motivation of a significant part of the contrast holding between strong verbs and their derivatives is to be found in ablaut, some correspondences between the strong verb and its derivatives clearly fall out of the scope of this phenomenon.
The framework of alternations as put forward by Kastovsky (1968) constitutes a double synthesis: firstly, of contrasts motivated by ablaut and by other phenomena and, secondly, of synchronic and diachronic facts.
Eventually, the phonological rules that produced ablaut were morphologized (Lass 1994; Kastovsky 2006; Ringe 2006).
83) Likewise, Machek, emphasizing the presence of ablaut
in Lithuanian, rejects the notion that Slavic vlad- represents a borrowing from Germanic.