This can be used as an alternative to phonological/phonotactic conditioning or in addition to it, for just those cases where there is more than one correspondence but no obvious phonological/phonotactic conditioning for the decision between phonemes.
even if only half or fewer of the Dutch words, for example, have the same vowel in cognates for which the english words have the same vowel, this still means that those half can be defined without the need for the language-specific vowel to be defined.