Xiao’erjing 小儿经/小儿锦 is the name given to the Arabic script when it is used to write any of the Chinese Languages by Chinese Muslims of different ethnicities and also by the Dungan (descendants of Chinese Muslims in Central Asia). The Dungans were however forced by the Soviets to convert to the Cyrillic script. Xiao’erjing should not be confused with Sini style of Arabic calligraphy developed by the Chinese Muslims. Xiao’erjing is mainly used for annotating religious texts. The Research Institute for Languages and Cultures in Japan has a repository of Xiao’erjing texts online.
P.S: Most of the website is in Japanese. It would be great if a Japanese speaker could enlighten us more about the website.