The document discusses the Sears List of Subject Headings (SLSH), which is a controlled vocabulary tool used to assign standardized subject headings in small to medium sized libraries. It has served unique needs of these libraries since its first edition in 1923. The SLSH is based on principles from the Library of Congress Subject Headings but modified for simplification in smaller libraries. It provides over 250 new subject headings in its latest edition that reflect changing needs and literature in areas like STEM. The SLSH has an alphabetical structure and aims to make library collections easy for users to access.