Query: POJ alphabet has been used since late in what century?
Context: Of these the most popular is Pe̍h-ōe-jī (traditional Chinese: 白話字; simplified Chinese: 白话字; pinyin: Báihuàzì). POJ was developed first by Presbyterian missionaries in China and later by the indigenous Presbyterian Church in Taiwan; use of this alphabet has been actively promoted since the late 19th century. The use of a mixed script of Han characters and Latin letters is also seen, though remains uncommon.