basis for standard Bosnian, Croatian, Montenegrin, and Serbian, has four "accents", which involve either a rising or falling tone on either long or short vowels, with optional post-tonic lengths: The tone stressed vowels can be approximated in English with set vs. setting? said in isolation for a short tonic e, or leave vs. leaving? for a long tonic i, due to the prosody of final stressed syllables in English. General accent rules in the standard language: Monosyllabic words may have only a falling tone (or no accent at all – enclitics); Falling tone may occur only on the first syllable of polysyllabic words; Accent can never occur on the last syllable of polysyllabic words. There are no other rules for accent placement, thus the accent of every word must be learned individually; furthermore, in inflection, accent shifts are common, both in type and position (the so-called "mobile paradigms"). The second rule is not strictly obeyed, especially in borrowed words. Comparative and historical linguistics offers some clues for memorising the accent position: If one compares many standard Serbo-Croatian words to e.g. cognate Russian words, the accent in the Serbo-Croatian word will be one syllable before the one in the Russian word, with the rising tone. Historically, the rising tone appeared when the place of the accent shifted to the preceding syllable (the so-called "Neo-Shtokavian retraction"), but the quality of this new accent was different – its melody still "gravitated" towards the original syllable. Most Shtokavian (Neo-Shtokavian) dialects underwent this shift, but Chakavian, Kajkavian and the Old-Shtokavian dialects did not. Accent diacritics are not used in the ordinary orthography, but only in the linguistic or language-learning literature (e.g. dictionaries, orthography and grammar books). However, there are very few minimal pairs where an error in accent can lead to misunderstanding. Orthography Serbo-Croatian orthography is almost entirely phonetic. Thus, most words should be spelled as they are pronounced. In practice, the writing system does not take into account allophones which occur as a result of interaction between words: bit ćepronounced biće (and only written separately in Bosnian and Croatian) od togapronounced otoga (in many vernaculars) iz čegapronounced iščega (in many vernaculars) Also, there are some exceptions, mostly applied to foreign words and compounds, that favor morphological/etymological over phonetic spelling: postdiplomski (postgraduate)pronounced pozdiplomskiOne systemic exception is that the consonant clusters ds and dš are not respelled as ts and tš (although d tends to be