What is the basis upon which a scholar's ijtihad (independent reasoning) is considered a madhhab (school of thought), and what is the criterion by which a scholar is attributed to a specific madhhab, even if they have reached the rank of absolute ijtihad?

A madhhab (school of thought) is the belief to which a scholar adheres, and it comprises the opinions of an absolute mujtahid Imam (a qualified independent jurist) and the evidence and rulings he has derived. Mujtahids are divided into four categories:

1. The Absolute Mujtahid: One who fulfills the conditions of ijtihad (independent legal reasoning), is independent in deriving rulings from the Sharia (Islamic law) evidence, and is not bound by anyone's madhhab. 2. Mujtahid within the Madhhab of His Imam: He follows the path of his Imam in ijtihad and is independent in establishing rulings based on evidence within the principles of his Imam, or he is a memorizer of the madhhab and knowledgeable of its evidence, or he is a memorizer of the madhhab and a transmitter of it. Their opinions are not attributed to them as a distinct madhhab because they are affiliated with the madhhab of their Imam. 3. Mujtahid in a Specific Type of Knowledge: He issues fatwas (religious edicts) on matters pertaining to a particular type of knowledge, such as inheritance or analogy (qiyas). 4. Mujtahid in Certain Issues or a Single Issue: He issues fatwas on limited issues, excluding others.