Overdot - Underdot

Underdot

• In IAST and National Library at Calcutta romanization, transcribing languages of India, a dot below a letter distinguishes the retroflex consonants ṭ, ḍ, ṛ, ḷ, ṇ, ṣ, while m with underdot (ṃ) signifies an anunaasika. Very frequently (in modern transliterations of Sanskrit) an underdot is used instead of the ring (diacritic) below the vocalic r and l.

• In romanizations of Semitic languages, a dot below a consonant indicates emphatic consonants. For example, ṣ represents an emphatic s.
  • Ḍ
  • Ṣ
  • Ṭ
  • Ẓ

• In Afro-Asiatic languages:
  • Ṛ

• In Asturian, ḷḷ (underdotted double ll) represents the voiced retroflex plosive, and ḥ (underdotted h) the voiceless glottal fricative.
• In O'odham language, Ḍ (d with underdot) represents a voiced retroflex stop.
• Vietnamese: The nặng tone (low, glottal) is represented with a dot below the base vowel: ạ ặ ậ ẹ ệ ị ọ ộ ợ ụ ự ỵ.
• In Yoruba, the dot is used below the o, the e and the s (ẹ, ọ, ṣ): those three letters can also occur without dot as another letter.
• In Igbo, an underdot can be used on i, o, and u to make ị, ọ, and ụ. The underdot symbolizes a reduction in the vowel height.
• In Americanist phonetic notation, x with underdot x̣ represents a voiceless uvular fricative.
• Underdots are used in the Rheinische Dokumenta phonetic writing system to denote a voiced s and special pronunciations of r and a.

The underdot is also used in the Devanagari script, where it is called nukta.