There are three vowel shifts that resulted in diphthongs: breaking, palatal diphthongization, and back mutation. Through breaking, Anglo-Frisian short developed into the short diphthongs , , before or a consonant cluster beginning with , and Anglo-Frisian long developed into the diphthongs and before . Palatal diphthongization changed , and , , and , to the diphthongs , , , respectively after the palatalized consonants , , and (though this may have only been a spelling change). Back mutation changed , , and sometimes to , , and before a back vowel in the next syllable.