The /‘/ is thus an intermittently present phoneme […] i.e. its presence indicates that some but not all the repetitions of that utterance will have the segmental distinctions which it represents. This /‘/ occurs only in morphemes borrowed from Arabic, and may be said to indicate a learned or ‘foreign’ pronunciation of these morphemes, as against a native pronunciation without /‘/.
- Harris (1951), a pag.116, n.7