AUTHOR MARK: use letter mark

It reports the results of a descriptive research with a qualitative approach, conducted through study and analysis of the literature related to the letter mark, which consists of the use of the first three letters of the author's last name to construct the author notation, which integrates the call number. It was observed that the theme is little treated in the national and foreign literature, and when this happens it is superficial. It used the original documents of Louis Stanley Jast (1868-1944), an author who first proposed the use of the letter mark. Thus, this study describes the methodology proposed by Jast (1901a, 1901b) for the construction of the letter mark, including guidelines for authors whose surnames begin with the same letters, work mark, fiction, copies, related works. The literature of the area was also rescued and consolidated, as well as pointed positive and negative points of Jast methodology.