In some environments it is impossible to write the letter ʒ, while all other letters of ISO 646 are available. Unused letters in Uropi are q, x, y. The desired sound /ʒ/ is
- voiced palato-alveolar sibilant @ https://en.wikipedia.org/wiki/Voiced_palato-alveolar_sibilant
- voiced postalveolar fricative @ https://www.internationalphoneticassociation.org/content/ipa-pulmonic-consonants
- q - in IPA is /q/ voiceless uvular stop (Wikipedia) or voiceless uvular plosive (IPA website)
- x - has the value /ks/ in several alphabets, which is voiceless, in IPA it is /x/ voiceless velar fricative
- y - has the value /j/ in several alphabets. /j/ is voiced palatal approximant
Some IALs use j = /ʒ/ and y = /j/. Choosing j = /j/ and y = /ʒ/ increases the compliance with IPA without changing any other letter.