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).