The dotless ı may also be used as a stylistic variant of the dotted i, without there being any meaningful difference between them.
This is common in older Irish orthography, for example, but is simply the omission of the tittle rather than a separate letter. The í is a separate letter as is ì in Scottish Gaelic. Though historically Irish only used an "i" without a dot, so as to not confuse with "í", this dotless "ı" should not be used for Irish. Instead a font with "i" in the normal location should be used that has no dot. See other old-style Irish letters and the symbol for & still used in modern Irish text and Irish orthography.
Lowercase dotless ı is used as the lowercase form of the letter Í in the official Karakalpak alphabet approved in 2016.
Both the dotted and dotless I can be used in transcriptions of Rusyn to allow distinguishing between the letters Ы and И, which would otherwise be both transcribed as "y", despite representing different phonemes. Under such transcription the dotted İ would represent the Cyrillic І, and the dotless I would represent either Ы or И, with the other being represented by "Y".
See also
Yery (ы), a letter used to represent Шаблон:IPAblink in Turkic languages with Cyrillic script, and the similar Шаблон:IPAblink in Russian
I with bowl, a letter that represented Шаблон:IPAblink in the Latin-based Yañalif alphabet used for the Turkic languages of the former Soviet Union prior to those languages' adoption of Cyrillic
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