The official Revised Romanization of Korean states that a hyphen should be used for separating different syllables, but an apostrophe is used instead for this purpose on English Wiktionary. This allows a hyphen to be used for semantic division only (e.g. 개울가 gae'ul-ga, consists of 개울 (gae'ul, “brook”) + 가 (ga, “edge”)).
Revised Romanization transliteration
In Article 3 Paragraph 8 of the 2000 edict establishing the Revised Romanization, provision is made for a system for academic use which represents the original hangul more precisely than standard RR. This system uses the standard jamo equivalents, without exception: for example, ㄱ is represented as "g" regardless of position and pronunciation. Thus for example 백 is baeg, and 막히다 is maghida (cf. baek, makhida in the standard system). In addition, syllable-initial ㅇ is represented by a hyphen (an apostrophe on English Wiktionary). Thus "백이" is romanized "baeg-i" ("baeg'i" on English Wiktionary) while "배기" is romanized "baegi."
RR transliteration is almost entirely unambiguous in its representation of written Korean. However, it does not represent pronunciation clearly.
In general, it is expected that McCune–Reischauer romanizations will follow the original 1939 system, with necessary adjustments based on the phonetics of modern Korean.
Yale is the only romanization system which represents both the written and the spoken form of Korean words without ambiguity. However, it is seldom used outside of the linguistic community.
The variant of Yale used for Middle Korean is the only romanization in use for that language.