Nasalization

The use of the ogonek to indicate nasality is common in the transcription of the indigenous languages of the Americas. This usage originated in the orthographies created by Christian missionaries to transcribe these languages. Later, the practice was continued by Americanist anthropologists and linguists who still, to the present day, follow this convention in phonetic transcription (see Americanist phonetic notation).

The ogonek is also used to indicate a nasalized vowel in Polish, academic transliteration of Proto-Germanic, Old Church Slavonic, Navajo, Western Apache, Chiricahua, Tłįchǫ Yatiì, Slavey, Dëne Sųłiné and Elfdalian. In Polish, ę is nasalized e; however, ą is nasalized o, not a, because of a vowel shift: ą, originally a long nasal a, turned into a short nasal o when the distinction in vowel quantity disappeared.

Length

In Lithuanian, the nosinė (literally, "nasal") mark originally indicated vowel nasalization but around late 17th and early 18th century, nasal vowels gradually evolved into the corresponding long non-nasal vowels in most dialects. Thus, the mark is now de facto an indicator of vowel length (the length of etymologically non-nasal vowels is marked differently or not marked at all). The mark also helps to distinguish different grammatical forms with otherwise the same written form (often with a different word stress, which is not indicated directly in the standard orthography).

Lowered articulation

Between 1927 and 1989, the ogonek denoted lowering in vowels, and, since 1976, in consonants as well, in the International Phonetic Alphabet (IPA). While the obsolete diacritic has also been identified as the left half ring diacritic ⟨◌̜⟩, many publications of the IPA used the ogonek.^[4]

In Rheinische Dokumenta, it marks vowels that are more open than those denoted by their base letters Ää, Oo, Öö. In two cases, it can be combined with umlaut marks.

E caudata and o caudata

The E caudata (ę), a symbol similar to an e with ogonek, evolved from a ligature of a and e in medieval scripts, in Latin and Irish palaeography. The O caudata of Old Norse^[5] (letter ǫ, with ǫ́)^[6][7] is used to write the open-mid back rounded vowel, /ɔ/. Medieval Nordic manuscripts show this 'hook' in both directions, in combination with several vowels.^[8] Despite this distinction, the term 'ogonek' is sometimes used in discussions of typesetting and encoding Norse texts, as o caudata is typographically identical to o with ogonek. Similarly, the E caudata was sometimes used to designate the Norse vowel [ɛ] or [æ].

Cedilla and comma

The ogonek is functionally equivalent to the cedilla and comma diacritic marks. If two of these three are used within the same orthography their respective use is restricted to certain classes of letters, i.e. usually the ogonek is used with vowels whereas the cedilla is applied to consonants. In handwritten text, the marks may even look the same.

Superscript ogonek

In Old Norse and Old Icelandic manuscripts, there is an over-hook or curl that may be considered a variant of the ogonek. It occurs on the letters a᷎ e᷎ i᷎ o᷎ ø᷎ u᷎.

Encoding

Because attaching an ogonek does not affect the shape of the base letter, Unicode covers it with a combining diacritic, U+0328. There are a number of precomposed legacy characters, but new ones are not being added to Unicode (e.g. for ⟨æ̨⟩ or ⟨ø̨⟩).

LaTeX2e

In LaTeX2e, macro \k will typeset a letter with ogonek, if it is supported by the font encoding, e.g. \k{a} will typeset ą. (The default LaTeX OT1 encoding does not support it, but the newer T1 one does. It may be enabled by saying \usepackage[T1]{fontenc} in the preamble.)

However, \k{e} rather places the diacritic "right-aligned" with the carrying e (ę), suitably for Polish, while \textogonekcentered horizontally centers the diacritic with respect to the carrier, suitably for Native American Languages as well as for e caudata and o caudata. So \textogonekcentered{e} better fits the latter purposes. Actually, \k{o} (for ǫ) is defined to result in \textogonekcentered{o}, and \k{O} is defined to result in \textogonekcentered{O}.^[9]

The package TIPA, activated by using the command "\usepackage{tipa}", offers a different way: "\textpolhook{a}" will produce ą.