phonology is generally described this way. Many languages forbid superheavy syllables, while a significant number forbid any heavy syllable. Some languages strive for constant syllable weight; for example, in stressed, non-final syllables in Italian, short vowels co-occur with closed syllables while long vowels co-occur with open syllables, so that all such syllables are heavy (not light or superheavy). The difference between heavy and light frequently determines which syllables receive stress – this is the case in Latin and Arabic, for example. The system of poetic meter in many classical languages, such as Classical Greek, Classical Latin, Old Tamil and Sanskrit, is based on syllable weight rather than stress (so-called quantitative rhythm or quantitative meter). Syllabification Syllabification is the separation of a word into syllables, whether spoken or written. In most languages, the actually spoken syllables are the basis of syllabification in writing too. Due to the very weak correspondence between sounds and letters in the spelling of modern English, for example, written syllabification in English has to be based mostly on etymological i.e. morphological instead of phonetic principles. English written syllables therefore do not correspond to the actually spoken syllables of the living language. Phonotactic rules determine which sounds are allowed or disallowed in each part of the syllable. English allows very complicated syllables; syllables may begin with up to three consonants (as in strength), and occasionally end with as many as five (as in angsts, pronounced [æŋsts]). (Some dialects of English pronounce strengths with a four-consonant onset, and angsts with a five-consonant coda: [stʃɹɛŋkθ] and [æŋksts] respectively.) Many other languages are much more restricted; Japanese, for example, only allows and a chroneme in a coda, and theoretically has no consonant clusters at all, as the onset is composed of at most one consonant. The linking of a word-final consonant to a vowel beginning the word immediately following it forms a regular part of the phonetics of some languages, including Spanish, Hungarian, and Turkish. Thus, in Spanish, the phrase ('the men') is pronounced , Hungarian ('the human') as , and Turkish ('I hated it') as . In Italian, a final sound can be moved to the next syllable in enchainement, sometimes with a gemination: e.g., ('I've never had any of them') is broken into syllables as and ('I go there and she does as well') is realized as . A related phenomenon, called consonant mutation, is found in the Celtic