The Vancouver system, also known as Vancouver reference style or the author–number system, is a citation style that uses numbers within the text that refer to numbered entries in the reference list. It is popular in the physical sciences and is one of two referencing systems normally used in medicine, the other being the author–date, or "Harvard", system. Vancouver style is used by MEDLINE and PubMed.

Hundreds of scientific journals use author–number systems. They all follow the same essential logic (that is, numbered citations pointing to numbered list entries), although the trivial details of the output mask, such as punctuation, casing of titles, and italic, vary widely among them. They have existed for over a century; the names "Vancouver system" or "Vancouver style" have existed since 1978. The latest version of the latter is Citing Medicine, per the References > Style and Format section of the ICMJE Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. These recommendations, the Vancouver Convention and Vancouver guidelines, have a much broader scope than only the citation style: they provide ethical guidelines for writers and rules for co-authorship in scientific collaborations to avoid fraud. The Convention further entails compliance with the Helsinki Declaration, and research projects must be recommended by an independent ethics committee.

In the broad sense, the Vancouver system refers to any author–number system regardless of the formatting details. A narrower definition of the Vancouver system refers to a specific author–number format specified by the ICMJE Recommendations (Uniform Requirements for Manuscripts, URM). For example, the AMA reference style is Vancouver style in the broad sense because it is an author–number system that conforms to the URM, but not in the narrow sense because its formatting differs in some minor details from the NLM/PubMed style (such as what is italicized and whether the citation numbers are bracketed).

 

Note:   The above text is excerpted from the Wikipedia article Vancouver system, which has been released under the GNU Free Documentation License.