A numerical indicator within a printed or digital volume denoting a specific location in the sequential arrangement of content. For instance, a reference to “15” guides the reader directly to the fifteenth unit of the ordered text within that compilation.
These location markers provide crucial navigational structure, facilitating efficient referencing, cross-referencing, and indexing of information. Their consistent presence across publications has been instrumental in scholarly communication and the organization of knowledge throughout history, enabling precise citation and verification of sources.