Korean in South Korea from 1984 to 2000, and yet a different modification is still the official system in North Korea. MR uses breves, apostrophes and diereses, the latter two indicating orthographic syllable boundaries in cases that would otherwise be ambiguous. Several variants of MR, often also called "McCune's and Reischauer's", differ from the original mostly in whether word endings are separated from the stem by a space, by a hyphen or not at all; and if a hyphen or space is used, whether sound change is reflected in a stem's last and an ending's first consonant letter (e.g. pur-i vs. pul-i). Although mostly irrelevant when transcribing uninflected words, these variants are so widespread that any mention of "McCune–Reischauer romanization" may not necessarily refer to the original system as published in the 1930s. MR-based romanizations have been common in popular literature until 2000. The ALA-LC / U.S. Library of Congress system is based on but deviates from MR. Unlike in MR, it addresses word division in seven pages of detail. Syllables of given names are always separated with a hyphen, which is expressly never done by MR. Sound changes are ignored more often than in MR. ALA-LC also distinguishes between ‘ and ’. Yale (1942): This system has become the established standard romanization for Korean among linguists. Vowel length in old or dialectal pronunciation is indicated by a macron. In cases that would otherwise be ambiguous, orthographic syllable boundaries are indicated with a period. This system also indicates consonants that have disappeared from a word's South Korean orthography and standard pronunciation. ISO/TR 11941 (1996): This actually is two different standards under one name: one for North Korea (DPRK) and the other for South Korea (ROK). The initial submission to the ISO was based heavily on Yale and was a joint effort between both states, but they could not agree on the final draft. A superficial comparison between the two is available here: Lukoff romanization, developed 1945–47 for Fred Lukoff’s Spoken Korean coursebooks Romanization of Korean (1992): the official romanization in North Korea. McCune–Reischauer-based transcriptions and the Revised Romanization differ from each other mainly in the choice of how to represent certain hangul letters. Both attempt to match a word's spelling to how it would be written if it were an English word, so that an English speaker would come as close as possible to its Korean pronunciation by pronouncing it