Where ⟨ʔ⟩ is not available, not being in the basic Latin alphabet, it is sometimes replaced by a question mark⟨?⟩, which is its official representation in the SAMPA transcription scheme. In Skwomesh or Squamish, ⟨ʔ⟩ may be replaced by the digit ⟨7⟩ (see image).
In Unicode, four graphic variants of the glottal stop letter are available.
A case pair, uppercase ⟨Ɂ⟩ (U+0241ɁLATIN CAPITAL LETTER GLOTTAL STOP) and lowercase ⟨ɂ⟩ (U+0242ɂLATIN SMALL LETTER GLOTTAL STOP), is provided for the orthographies of Athabaskan languages in the Northwest Territories. Uppercase ⟨Ɂ⟩ may be slightly wider than unicase ⟨ʔ⟩ in fonts that distinguish them.
Other common symbols for the glottal stop sound are variants of the punctuation mark apostrophe that was the historical basis of the glottal stop letters. These include the 9-shaped modifier letter apostrophe, ⟨ʼ⟩, which is probably the most common (and the direct ancestor of ⟨ʔ⟩), the 6-shaped ʻokina of Hawaiian, ⟨ʻ⟩, and the straight-apostrophe shaped saltillo of many languages of Mexico, which has the case forms ⟨Ꞌ ꞌ⟩.
In Unicode 1.0, only the unicase and superscript variants were included. In version 4.1 (2005), an uppercase character was added, and the existing unicase character was redefined as its lowercase. Then, in version 5.0 (2006), it was decided to separate the cased and caseless usages by adding a dedicated lowercase letter. The IPA character is first from left, while the extended Latin alphabet characters are third and fourth from left.[1]
