Question: what datasets were used?
Answer: diacritized corpus that was used to train the RDI BIBREF7 diacritizer and the Farasa diacritizer BIBREF31, WikiNews test set BIBREF31,  large collection of fully diacritized classical texts (2.7M tokens) from a book publisher
Alternative answer: the diacritized corpus that was used to train the RDI BIBREF7 diacritizer , WikiNews , a large collection of fully diacritized classical texts