Please answer a question about the following article about Freemasonry:

Since the middle of the 19th century, Masonic historians have sought the origins of the movement in a series of similar documents known as the Old Charges, dating from the Regius Poem in about 1425 to the beginning of the 18th century. Alluding to the membership of a lodge of operative masons, they relate a mythologised history of the craft, the duties of its grades, and the manner in which oaths of fidelity are to be taken on joining. The fifteenth century also sees the first evidence of ceremonial regalia.

What are the old Masonic document referred as?
Old Charges