The accession number in modern specimens is often represented as a machine readable barcode.

The barcode accession number is used in the database to link all the information related to this specimen, such as the species name, the information on the herbarium label, specimen components and storage, etc.

The barcode facilitates rapid handling and retrieval of information about specimens, for example in the preparation of lists of specimens examined or of loans and exchanges.

The most common barcode font used in herbaria is '3 of 9'.