Due to the orthographic principles of uniformity ('the spelling of a morpheme should be kept constant') and etymology ('the spelling of a word should take the etymology of that word into consideration'), more <h>s are written than are pronounced. Take the word hjouwer oat(s). Its pronunciation is [jɔwər], which is indistinguishable from that of jouwer /jɔw+ər/ giver; it is, however, written with <h>-, which can be motivated on etymological grounds, see the cognates haver (Dutch) and Hafer (German). Take, furthermore, an alternation such as hier /hiər/ hair ~ hierrich [jɪrəx] hairy; though hierrich is pronounced without [h-], it is written with <h>-, because of its relation with hier.

An overview of the contexts in which word-initial /h/ has been deleted is given in (1).

As is clear, /h/ has systematically been deleted in case it preceded a glide. From a synchronic view point, Breaking is an opaque phenomenon, so it cannot be dealt with in purely phonological terms. The relation between a form with a centring diphthong and the one with the corresponding glide + vowel sequence therefore is one of allomorphy. For cases such as those in (1c-d) two stem allomorphs must be assumed, one with /h/ followed by a centralizing diphthong and one with merely a rising diphthong. The words in (1a-b) can safely be assumed to no longer have /h/ in their underlying representation.

Not only was /h/ deleted in case it preceded the broken diphthongs /wa/ and /wo/, it was also replaced by the labiodental fricative /v/, as shown by words like hoanne [vwanə] cock, hoart [vwat] thrust, dig; time, while, huorde [vwodə] hoard, hoazzen [vwa:zn̩] stockings, and huodden [vwodn̩] hats. This appearance of /v/, however, is an independent phenomenon, which also manifested itself in words beginning with just a broken diphthong, like oarberje [vwarbərjə] consume, dispatch, oarder [vwadr̩] order, oargel [vwarɣəl] (pipe) organ, oarre#mem [vwarə-] grandmother, Oark [vwark] men's name, oartsen [vwatsn̩] old coin (farthing), and uorre#moarn [vworə-] the day after tomorrow. This means that words with initial /h/ + broken diphthong and those beginning with just a broken diphthong have acquired the same onset as those beginning with the sequence /v/ + broken diphthong, examples of which are woarst [vwast] sausage, woartel [vwatl̩] root; carrot, and wuolje [vwoljə] to wind; to wrap (up). All in all then it is not the case that initial /h/ was 'replaced by' the labiodental fricative /v/. All one can say is that the deletion of the former paved the way for the development of the latter.

There is an independent piece of evidence for the presence of /v/ here. In the Wâldfrysk dialect, the sequence labial consonant + /w{a/o}/ has generally turned into labial consonant + /j{a/o}/, which means that the glide /w/ has been replaced by the glide /j/ (see replacement of the glide /w/ of the broken diphthong /w{a/o}/ by /j/ following labial consonants). This has also affected words like those above, so hoanne [vwanə] cock, oargel [vwarɣəl] (pipe) organ, woarst [vwast] sausage, and huodden [vwodn̩] hats, for instance, are now realized with initial [vj{a/o}], as [vjanə], [vjarɣəl], [vjast], and [vjodn̩], respectively. It is due to their initial labiodental /v/ that the words in question could, and did, join this pattern.

The glide /w/ then seems to be prohibited in word-initial position. Though segments with the lowest degree of sonority are favoured in the onset position, glides are not prohibited there, as shown by the large number of words which begin with /j/. There is, however, a difference between /j/ and /w/. Diachronically speaking, the word-initial bilabial glide /w/ has turned into the labiodental fricative /v/, as a consequence of which the newly arisen word-initial /w/ was likely to be felt as deviant. The glides are realized with some (phonetic) frication in word-initial position. This was easily reinterpreted as a consonantal feature, the more so because of /w/'s exceptionality there. The fact that /w/ was reinterpreted as /vw/ need not come as a surprise: on the one hand, labio-dental /v/ and labio-velar /w/ have much in common whereas, on the other hand, they are sufficiently different to count as separate segments.