External Identifier: The <journal-id> element holds an external identifier, typically assigned to a journal by a publisher, archive, or library to provide a unique identifier for the journal. The contents of this element should not be confused with the @id attribute, which holds an internal document identifier that can be used by software to preform a simple link inside the document.

There may be more than one such identifier, with the type of identifier named by the @journal-id-type attribute. For example, one identifier may be a registered DOI, another a control number assigned by the publisher, and another the journal abbreviation assigned by PubMed Central.

For NLM’s PubMed Central and other NLM-internal processing, this element contains an alternative to, or short form of, the journal title, used to identify the journal domain. In such processing, this element is the equivalent to, and usually used instead of, the <abbrev-journal-title> element. Outside PubMed Central processing, this use of the <journal-id> element is rare; journal tag sets typically use the <abbrev-journal-title> element to hold the short version of a journal title and the <issn> element to hold a journal identifier, rather than creating a separate identifier for the journal. For journals that have assigned an non-ISSN identifier (typically numeric) for individual journal titles, this <journal-id> element can hold that identifier.

Best Practice: This element should not be confused with or used for the <issn> or <isbn> information, which are individual elements in this Tag Set.

NLM PubMed Central Authoring/Conversion Note: In PubMed Central processing, the short journal title identifiers used in this element come from an authorized list, so that each journal code is unique within the PubMed Central system. The <journal-id> holds the PubMed Central short abbreviation of the journal title, which identifies the journal domain. The content of this element may thus be repeated in the <abbrev-journal-title> element, or the publisher’s abbreviation may be used in the <abbrev-journal-title> element.