Jewish Arabic texts with Hebrew pointing

This is a really interesting image, because I say so.

Actually, it's interesting, I think, because while it was written in the Arabic alphabet, it uses Hebrew vowel points. The manuscript is Karaitic, and the practice was not uncommon in Karaite writings in Arabic, whereas Rabbanite writings in Arabic invariably used the Hebrew alphabet.

It's quite striking, because Arabic has its own system of diacritics. Why Rabbanites chose not to use--or didn't learn--the Arabic alphabet, and why Karaites did, but chose not to use--or didn't learn--the Arabic vowels is an interesting question. Speculators welcome.