omission of apostrophe-like characters, the four sounds represented in Hànyǔ Pīnyīn by j, q, zh, and ch often all become ch, including in many proper names. However, if the apostrophe-like characters are kept, the system reveals a symmetry that leaves no overlap: The non-retroflex ch (Pīnyīn j) and ch (Pīnyīn q) are always before either ü or i, but never ih. The retroflex ch (Pīnyīn zh) and ch (Pīnyīn ch) are always before ih, a, ê, e, o, or u. Vowels and final symbols Syllabic consonants Like Yale and Mandarin Phonetic Symbols II, Wade–Giles renders the two types of syllabic consonant (; Wade–Giles: kung1-yün4; Hànyǔ Pīnyīn: kōngyùn) differently: -ŭ is used after the sibilants written in this position (and this position only) as tz, tz and ss (Pīnyīn z, c and s). -ih is used after the retroflex ch, ch, sh, and j (Pīnyīn zh, ch, sh, and r). These finals are both written as -ih in Tongyòng Pinyin, as -i in Hànyǔ Pīnyīn (hence distinguishable only by the initial from as in li), and as -y in Gwoyeu Romatzyh and Simplified Wade. They are typically omitted in Zhùyīn (Bōpōmōfō). Vowel o Final o in Wade–Giles has two pronunciations in modern Peking dialect: and . What is pronounced in vernacular Peking dialect as a close-mid back unrounded vowel is written usually as ê, but sometimes as o, depending on historical pronunciation (at the time Wade–Giles was developed). Specifically, after velar initials k, k and h (and a historical ng, which had been dropped by the time Wade–Giles was developed), o is used; for example, "哥" is ko1 (Pīnyīn gē) and "刻" is ko4 (Pīnyīn kè). In Peking dialect, o after velars (and what used to be ng) have shifted to , thus they are written as ge, ke, he and e in Pīnyīn. When forms a syllable on its own, Wade–Giles writes ê or o depending on the character. In all other circumstances, it writes ê. What is pronounced in Peking dialect as is usually written as o in Wade–Giles, except for wo, shuo (e.g. "說" shuo1) and the three syllables of kuo, kuo, and huo (as in 過, 霍, etc.), which contrast with ko, ko, and ho that correspond to Pīnyīn ge, ke, and he. This is because characters like 羅, 多, etc. (Wade–Giles: lo2, to1; Pīnyīn: luó, duō) did not originally carry the medial . Peking dialect does