U+00EF LATIN SMALL LETTER I WITH DIAERESIS

U+00EF was added to Unicode in version 1.1. It belongs to the block Latin-1 Supplement in the Basic Multilingual Plane.

This character is a Lowercase Letter and is mainly used in the Latin script. It is related to its uppercase variant 00CF and its titlecase variant 00CF.

The glyph is a Canonical composition of the glyphs 0069 0308. It has a Neutral East Asian Width. In bidirectional context it acts as Left To Right and is not mirrored. In text U+00EF behaves as Alphabetic regarding line breaks. It has type Lower for sentence and ALetter for word breaks. The Grapheme Cluster Break is Any.

The Wikipedia has the following information about this codepoint:

Ï, lowercase ï, is a symbol used in various languages written with the Latin alphabet; it can be read as the letter I with diaeresis or I-umlaut.

In Afrikaans, Catalan, Dutch, French, Galician, Welsh, Southern Sami, and occasionally English, ⟨ï⟩ is used when ⟨i⟩ follows another vowel and indicates hiatus (diaeresis) in the pronunciation of such a word—that is, it indicates that the two vowels are pronounced in separate syllables, rather than together as a diphthong or digraph. For example, French maïs (IPA: [ma.is], maize); without the diaeresis, the ⟨i⟩ is part of the digraph ⟨ai⟩: mais (IPA: [mɛ], but). The letter is also in Dutch Oekraïne (IPA: [ukrɑːˈinə], Ukraine), and English naïve (pronounced /nɑːˈiːv/ or /naɪˈiːv/).

In the transcription of the languages of the Amazon, ï is used to represent the high central vowel [ɨ].