For example: mathematical symbols? (lowercase? ) was originally a letter in Nordic languages such as Denmark and Norway. Its name is the same as its pronunciation, and its pronunciation is similar to the pronunciation of o in English words. What is the diameter symbol? , with letters and empty set symbols? It's all different. They have nothing to do with the Greek letter φ. None of them can be pronounced as phi, the symbol of empty set is pronounced as "empty set" and the symbol of diameter is pronounced as "diameter".
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The diacritical marks are written above lowercase letters and above the left of uppercase letters. In the case of diphthongs or diphthongs, the second vowel accepts phonetic symbols. Breathing symbols are written to the left of acute notes or accents, but below the accented notes. Stress symbols are written above partials, and sharp sounds or stress symbols can also be written between two points.
In modern Greek, all stress symbols are unified into a substitute symbol, that is, acute notes. The use of breathing symbols is abandoned, but partials remain. Of course, if you use Greek letters as specific codes, you don't need to add additional symbols.