ts and s, Wade–Giles writes tz, tz and ss before ŭ (see below). Finals Wade–Giles writes -uei after k and k, otherwise -ui: kuei, kuei, hui, shui, chui. It writes as -o after k, k and h, otherwise as -ê: ko, ko, ho, shê, chê. When forms a syllable on its own, it is written ê or o depending on the character. Wade–Giles writes as -uo after k, k, h and sh, otherwise as -o: kuo, kuo, huo, shuo, cho. For -ih and -ŭ, see below. Giles's A Chinese–English Dictionary also includes the syllables chio, chio, hsio, yo, which are pronounced like chüeh, chüeh, hsüeh, yüeh in Peking dialect. Syllables that begin with a medial Wade–Giles writes the syllable as i or yi depending on the character. System features Consonants and initial symbols A feature of the Wade–Giles system is the representation of the unaspirated-aspirated stop consonant pairs using a character resembling an apostrophe. Thomas Wade and others have used the spiritus asper ( or ), borrowed from the polytonic orthography of the Ancient Greek language. Herbert Giles and others have used a left (opening) curved single quotation mark (‘) for the same purpose. A third group used a plain apostrophe ('). The backtick, and visually similar characters are sometimes seen in various electronic documents using the system. Examples using the spiritus asper: p, p, t, t, k, k, ch, ch. The use of this character preserves b, d, g, and j for the romanization of Chinese varieties containing voiced consonants, such as Shanghainese (which has a full set of voiced consonants) and Min Nan (Hō-ló-oē) whose century-old Pe̍h-ōe-jī (POJ, often called Missionary Romanization) is similar to Wade–Giles. POJ, Legge romanization, Simplified Wade, and EFEO Chinese transcription use the letter instead of an apostrophe-like character to indicate aspiration. (This is similar to the obsolete IPA convention before the revisions of the 1970s). The convention of an apostrophe-like character or to denote aspiration is also found in romanizations of other Asian languages, such as McCune–Reischauer for Korean and ISO 11940 for Thai. People unfamiliar with Wade–Giles often ignore the spiritus asper, sometimes omitting them when copying texts, unaware that they represent vital information. Hànyǔ Pīnyīn addresses this issue by employing the Latin letters customarily used for voiced stops, unneeded in Mandarin, to represent the unaspirated stops: b, p, d, t, g, k, j, q, zh, ch. Partly because of the popular