Subject access refers to the methods and systems by which books, journals, and other documents are accessed in a given bibliographic database (e.g. a library classification system).
Such searchable data from fields of records are termed access points.
Some of these access points contain information such as author name, number of pages, the language of publication, name of publisher ,etc.
Other kinds of access points contain information such as title words, classification codes, indexing terms ,etc.
In theory, any access point may hypothetically be used for subject searching.