have also undergone divergent developments in German and Yiddish. Where Standard German has merged the Middle High German diphthong ei and long vowel î to , Yiddish has maintained the distinction between them; and likewise, the Standard German corresponds to both the MHG diphthong öu and the long vowel iu, which in Yiddish have merged with their unrounded counterparts ei and î, respectively. Lastly, the Standard German corresponds to both the MHG diphthong ou and the long vowel û, but in Yiddish, they have not merged. Although Standard Yiddish does not distinguish between those two diphthongs and renders both as , the distinction becomes apparent when the two diphthongs undergo Germanic umlaut, such as in forming plurals: The vowel length distinctions of German do not exist in the Northeastern (Lithuanian) varieties of Yiddish, which form the phonetic basis for Standard Yiddish. In those varieties, the vowel qualities in most long/short vowel pairs diverged and so the phonemic distinction has remained. There are consonantal differences between German and Yiddish. Yiddish deaffricates the Middle High German voiceless labiodental affricate to initially (as in , but this pronunciation is also quasi-standard throughout northern and central Germany); /pf/ surfaces as an unshifted medially or finally (as in and ). Additionally, final voiced stops appear in Standard Yiddish but not Northern Standard German. Comparison with Hebrew The pronunciation of vowels in Yiddish words of Hebrew origin is similar to Ashkenazi Hebrew but not identical. The most prominent difference is kamatz gadol in closed syllables being pronounced same as patah in Yiddish but the same as any other kamatz in Ashkenazi Hebrew. Also, Hebrew features no reduction of unstressed vowels and so the given name Jochebed would be in Ashkenazi Hebrew but in Standard Yiddish. Patah in open syllable, as well as hataf patah, are unpredictably split between A1 and A2: ; . Grammar Yiddish grammar can vary slightly depending on the dialect. The main article focuses on standard form of Yiddish grammar while also acknowledging some dialectal differences. Yiddish grammar has similarities to the German grammar system, as well as grammatical elements from Hebrew and other Slavic languages. Writing system Yiddish is written in the Hebrew alphabet, but its orthography differs significantly from that of Hebrew. Whereas, in Hebrew, many vowels are represented only optionally by diacritical marks called niqqud, Yiddish uses letters to represent all vowels. Several Yiddish letters consist of another letter combined