Glottal stop
Some Canadian indigenous languages, especially some of the Salishan languages, use the letter ʔ itself as part of their writing systems. In some of them, there are uppercase and lowercase letters for the glottal stop: Ɂ and ɂ. The number 7 or question mark is sometimes used instead of ʔ. Some languages, such as Squamish, use this instead of ʔ. SENĆOŦEN uses the comma  to write the glottal stop. However, this is optional in SENĆOŦEN.