other diacritics: ä, ā, â, ã.) The tilde also marks nasality in the case of G̃/g̃, used to represent the nasalized velar approximant by combining the velar approximant "G" with the nasalising tilde. The letter G̃/g̃, which is unique to this language, was introduced into the orthography relatively recently during the mid-20th century and there is disagreement over its use. It is not a precomposed character in Unicode, which can cause typographic inconveniences – such as needing to press "delete" twice in some setups – or imperfect rendering when using computers and fonts that do not properly support the complex layout feature of glyph composition. Only stressed nasal vowels are written as nasal. If an oral vowel is stressed, and it is not the final syllable, it is marked with an acute accent: á, é, í, ó, ú, ý. That is, stress falls on the vowel marked as nasalized, if any, else on the accent-marked syllable, and if neither appears, then on the final syllable. For blind people there is also a Guarani Braille. Phonology Guarani syllables consist of a consonant plus a vowel or a vowel alone; syllables ending in a consonant or two or more consonants together do not occur. This is represented as (C)V. In the below table, the IPA value is shown. The orthography is shown in angle brackets below, if different. Consonants The voiced consonants have oral allophones (left) before oral vowels, and nasal allophones (right) before nasal vowels. The oral allophones of the voiced stops are prenasalized. There is also a sequence (written ). A trill (written ), and the consonants , , and (written ) are not native to Guarani, but come from Spanish. Oral is often pronounced , depending on the dialect, but the nasal allophone is always . The dorsal fricative is in free variation between and . , are approximants, not fricatives, but are sometimes transcribed , as is conventional for Spanish. is also transcribed , which is essentially identical to . All syllables are open, viz. CV or V, ending in a vowel. Glottal stop The glottal stop, called 'puso' in Guarani, is only written between vowels, but occurs phonetically before vowel-initial words. Because of this, Ayala (2000:19) shows that some words have several glottal stops near each other, which consequently undergo a number of different dissimilation techniques. For example, "I drink water" ayu is pronounced hayu. This suggests