Since each search engine has its own vocabulary and organizational scheme, a search using one search engine may turn up too many hits while the same search using a different search engine may result in no hits at all. Classification systems increase access by grouping, or collocating, information packages together according to their subject content. By establishing relationships between information packages, classification systems supply context and furnish end-users with a way to discover potentially helpful items. All Internet search engines do not use the same controlled vocabulary or organizational scheme. Once the relationships between the classes, subclasses, divisions and sections are established, library classification systems assign notation to each.
Notation is used to assign call numbers to individual information packages.
The call number assigned works as a collocation device. For a library, this means that information packages are ordered according to call number. Information packages that are related in some manner are shelved together using this number. This allows patrons to browse related items in a specific area of the stacks. Although it is a popular library use, there are limits to the effectiveness of browsing in a library's shelves.