Latin alphabets in the context of "Diacritics"

A Venn diagram is a widely used diagram style that shows the logical relation between sets, popularized by John Venn (1834–1923) in the 1880s. The diagrams are used to teach elementary set theory, and to illustrate simple set relationships in probability, logic, statistics, linguistics and computer science. A Venn diagram uses simple closed curves on a plane to represent sets. The curves are often circles or ellipses.

Similar ideas had been proposed before Venn such as by Christian Weise in 1712 (Nucleus Logicoe Wiesianoe) and Leonhard Euler in 1768 (Letters to a German Princess). The idea was popularised by Venn in Symbolic Logic, Chapter V "Diagrammatic Representation", published in 1881.

The ogonek, also informally referred to as the tail, is a diacritic hook placed under the lower right corner of a vowel grapheme in the Latin alphabets of Polish, Kashubian, Övdalian, and Lithuanian; and directly under a vowel in several Native American languages.

An ogonek can also be attached to the bottom of a vowel in Old Norse or Old Icelandic to show length or vowel affection. For example, in Old Norse, ǫ represents the Old Norwegian vowel [ɔ], which in Old Icelandic merges with ø ‹ö› and in modern Scandinavian languages is represented by the letter å.

The Vietnamese alphabet (Vietnamese: chữ Quốc ngữ, chữ Nôm: 𡨸國語, lit. 'script of the national language', IPA: [t͡ɕɨ˦ˀ˥ kuək̚˧˦ ŋɨ˦ˀ˥]) is the modern writing script for the Vietnamese language. It is a Latin-based script whose spelling conventions are derived from the orthography of Romance languages such as Portuguese, Italian, and French. It was originally developed by Francisco de Pina and other Jesuit missionaries in the early 17th century.

The Vietnamese alphabet contains 29 letters, including 7 letters using four diacritics: ⟨ă⟩, ⟨â⟩, ⟨ê⟩, ⟨ô⟩, ⟨ơ⟩, ⟨ư⟩, and ⟨đ⟩. There are an additional 5 diacritics used to designate tone (as in ⟨à⟩, ⟨á⟩, ⟨ả⟩, ⟨ã⟩, and ⟨ạ⟩). The complex vowel system and the large number of letters with diacritics, which can stack twice on the same letter (e.g. nhất meaning 'first'), makes it easy to distinguish the Vietnamese orthography from other writing systems that use the Latin alphabet.