In the original Assassin's Creed, what rank does Altaïr hold before Al Mualim demotes him?

Altaïr holds the rank of Master Assassin before Al Mualim demotes him in the original Assassin's Creed.

At the beginning of the game, Altaïr Ibn-La'Ahad is an accomplished senior member of the Levantine Assassin Brotherhood. During a failed mission beneath Solomon's Temple, his arrogance and actions jeopardize the operation. After Altaïr returns to Masyaf, his mentor Al Mualim strips him of rank and equipment.

The demotion serves both story and gameplay purposes. Altaïr must recover his status by completing a sequence of missions against targets connected to the Templars. As he succeeds, he regains abilities and learns that the political conflict is more complicated than it first appeared.

Master Assassin is distinct from the later series title Mentor, which refers to the leader of an Assassin Brotherhood. Altaïr eventually becomes a major leader himself, but the question asks specifically about his status before the opening mission's punishment.