It is the Arabic original of "The Guide for the Perplexed" of
Maimonides, in Hebrew letters. The reference says "The Guide for the
Perplexed : The Arabic original as published by Shelomo Ben-Eli'ezer
Munk: with alternative versions, indexes and sections handwritten by
the Rambam, Rabbi Moshe Ben Maimon"
Thank you!
Writing the local languages with Hebrew letters was quite common,
especially Arabic, German and Spanish (Castilian).
Interesting. There seems to be a pattern where small populations stick
to their script while learning the languages of the surrounding
populations (and writing both in their own script).
It seems that diacritic are used rather freely, both following Arabic
practice (I guess in cases the author thought it was necessary to
distinguish between similar words) and as the OP suggests to represent
phonemes missing in Hebrew.
Oh, btw I noticed that typesetting-wise there were no diacritics below
the letters, only above. Anyways, the question is answered.
Stephan