Also, aa, when used as an alternative spelling to å, is sorted as such.Other letters modified by diacritics are treated as variants of the underlying letter, with the exception that ü is frequently sorted as y.It first appeared in the 11th century in the sequence ii (as in ingeníí), then spread to i adjacent to m, n, u, and finally to all lowercase i's.The j, originally a variant of i, inherited the tittle.In abugida scripts, like those used to write Hindi and Thai, diacritics indicate vowels, and may occur above, below, before, after, or around the consonant letter they modify.The tittle (dot) on the letter i of the Latin alphabet originated as a diacritic to clearly distinguish i from the minims (downstrokes) of adjacent letters.Languages that treat accented letters as variants of the underlying letter usually alphabetize words with such symbols immediately after similar unmarked words. in phone books or in author catalogues in libraries), umlauts are often treated as combinations of the vowel with a suffixed e; Austrian phone books now treat characters with umlauts as separate letters (immediately following the underlying vowel).For instance, in German where two words differ only by an umlaut, the word without it is sorted first in German dictionaries (e.g. In Spanish, the grapheme ñ is considered a new letter different from n and collated between n and o, as it denotes a different sound from that of a plain n.
In some cases, letters are used as "in-line diacritics", with the same function as ancillary glyphs, in that they modify the sound of the letter preceding them, as in the case of the "h" in the English pronunciation of "sh" and "th".
In other alphabetic systems, diacritical marks may perform other functions.
Vowel pointing systems, namely the Arabic harakat ( ), which, respectively, mark abbreviations or acronyms, and Greek diacritical marks, which showed that letters of the alphabet were being used as numerals.
Modern computer technology was developed mostly in English-speaking countries, so data formats, keyboard layouts, etc.
were developed with a bias favoring English, a language with an alphabet without diacritical marks.
In the Wali language of Ghana, for example, an apostrophe indicates a change of vowel quality, but occurs at the beginning of the word, as in the dialects ’Bulengee and ’Dolimi.