Additional identifier for the publication where the resource appeared, providing the Volume portion of the common Volume, Number scheme. :related-item prism:volume "1" . has volume This is used to express the volume number of a resource. Provided for basic bibliographic citations. The content should not contain “Vol.” or other abbreviations for “Volume”; it should only be the alphanumeric volume identifier. The Number portion of the issue identification is specified in the prism:number element.