I am currently working with the Pechanga Nation and the company,
IconNicholson. The standard orthography of the Luiseño language, spoken at
Pechanga and several other communities in Southern California, requires
two characters which I believe are currently absent from Unicode.
The characters are "majuscule S with a diagonal stroke", and "minuscule s
with a diagonal stroke". This letter is used to represent a voiceless
retroflex fricative, which is distinct from the alveolar fricative "s" and
the palato-alveolar "sh".