I want to know the answer to the following question:
What field does the ijazah signify expertise in?
All the background I'm provided with is that "In contrast to the medieval doctorate which was granted by the collective authority of the faculty, the Islamic degree was not granted by the teacher to the pupil based on any formal criteria, but remained a "personal matter, the sole prerogative of the person bestowing it; no one could force him to give one".". Is that enough to answer the question?
Answer: no