Editing International Phonetic Alphabet (section)

== Obsolete and nonstandard symbols ==
{{Main|Obsolete and nonstandard symbols in the International Phonetic Alphabet|Click letter|Sinological extensions to the International Phonetic Alphabet}}

A number of IPA letters and diacritics have been retired or replaced over the years. This number includes duplicate symbols, symbols that were replaced due to user preference, and unitary symbols that were rendered with diacritics or digraphs to reduce the inventory of the IPA. The rejected symbols are now considered obsolete, though some are still seen in the literature.

The IPA once had several pairs of duplicate symbols from alternative proposals, but eventually settled on one or the other. An example is the vowel letter {{angbr IPA|ɷ}}, rejected in favor of {{angbr IPA|ʊ}}. Affricates were once transcribed with ligatures, such as {{angbr IPA|ʧ ʤ&thinsp;}} (and others, some of which not found in Unicode). These have been officially retired but are still used. Letters for specific combinations of primary and secondary articulation have also been mostly retired, with the idea that such features should be indicated with tie bars or diacritics: {{angbr IPA|ƍ}} for {{IPA|[zʷ]}} is one. In addition, the rare voiceless implosives, {{angbr IPA|ƥ ƭ ƈ ƙ ʠ&thinsp;}}, were dropped soon after their introduction and are now usually written {{angbr IPA|ɓ̥ ɗ̥ ʄ̊ ɠ̊ ʛ̥&thinsp;}}. The original set of click letters, {{angbr IPA|ʇ, ʗ, ʖ, ʞ}}, was retired but is still sometimes seen, as the current pipe letters {{angbr IPA|ǀ, ǃ, ǁ, ǂ}} can cause problems with legibility, especially when used with brackets ([ ] or / /), the letter {{angbr IPA|l}} (small L), or the [[prosodic]] marks {{angbr IPA|<nowiki>|</nowiki>, ‖}}. (For this reason, some publications which use the current IPA pipe letters disallow IPA brackets.<!--The Routledge Khoisan Handbook, for example.-->)<ref>{{cite web |last=Wells |first=John |date=9 September 2009 |title=click symbols |url=http://phonetic-blog.blogspot.com/2009/09/click-symbols.html |access-date=18 October 2010 |website=John Wells's phonetic blog |archive-date=30 November 2018 |archive-url=https://web.archive.org/web/20181130213700/http://phonetic-blog.blogspot.com/2009/09/click-symbols.html |url-status=live}}</ref>

Individual non-IPA letters may find their way into publications that otherwise use the standard IPA. This is especially common with:
* Affricates, such as the Americanist [[barred lambda]] {{angbr IPA|ƛ}} for {{IPA|[t͜ɬ]}} or {{angbr IPA|č}} for {{IPA|[t͜ʃ&thinsp;]}}.{{NoteTag|The motivation for this may vary. Some authors find the tie bars displeasing but the lack of tie bars confusing (i.e. {{angbr IPA|č}} for {{IPA|/t͡ʃ/}} as distinct from {{IPA|/tʃ/}}), while others simply prefer to have one letter for each segmental phoneme in a language.{{citation needed|date=September 2020}}}}
* The [[Karlgren]] letters for Chinese vowels, {{angbr IPA|ɿ, ʅ&thinsp;, ʮ, ʯ&thinsp;}}.
* Digits for tonal phonemes that have conventional numbers in a local tradition, such as the [[Standard Chinese phonology#Tones|four tones of Standard Chinese]]. This may be more convenient for comparison between related languages and dialects than a phonetic transcription would be, because tones vary more unpredictably than segmental phonemes do.
* Digits for tone levels, which are simpler to typeset, though the lack of standardization can cause confusion (e.g. {{angbr IPA|1}} is high tone in some languages but low tone in others; {{angbr IPA|3}} may be high, medium or low tone, depending on the local convention).
* Iconic extensions of standard IPA letters that are implicit in the alphabet, such as retroflex {{IPAalink|ᶑ}} and {{IPAalink|ꞎ}}. These are referred to in the ''Handbook'' and have been included in Unicode at IPA request.<!--e.g. an official request for adding superscript retroflex letters to Unicode 14.-->
* Even presidents of the IPA have used para-IPA notation, such as resurrecting the old diacritic {{angbr IPA|◌̫}}<!--Ladefoged--> for purely labialized sounds (not simultaneously velarized), the lateral fricative letter {{angbr IPA|ꞎ&thinsp;}},<!--Ladefoged--> and either the old dot diacritic {{angbr IPA|ṣ ẓ}}<!--Ladefoged--> or the novel letters {{angbr IPA|&thinsp;ᶘ ᶚ}}<!--Laver--> for the not-quite-retroflex fricatives of Polish ''sz, ż'' and of Russian ''ш ж''.

In addition, it is common to see ''ad hoc'' typewriter substitutions, generally capital letters, for when IPA support is not available, e.g. S for {{angbr IPA|&thinsp;ʃ&thinsp;}}. (See also [[SAMPA]] and [[X-SAMPA]] substitute notation.)