Holds one of the “unique identifiers” that have been assigned at various times to an article; each <article-id> stores one such identifier.
There may be many identifiers for a single article or there may not be any at all. While each is a “unique identifier” in some system, an article may be identified in many systems. The content for this element may come from a publisher, a jobber, or NLM PubMed Central (PMC), for example. Examples of such identifiers include the publisher’s tracking number, the PNAS number, etc.
The pub-id-type attribute may be used to name the type of identifier (such as DOI or SICI), or the organization or system (such as MEDLINE) that defined this identifier. This attribute need only be used if the type is known, for example, to identify DOIs explicitly.
Conversion Note: An archive may attempt to carry all the identifiers associated with an article. For example, during conversion PMC will create <article-id>s for identifiers that come from the publisher as elements or as attributes on the original article.
<!ELEMENT article-id (#PCDATA) >
Text, numbers, or special characters
... <front> <journal-meta> <journal-id journal-id-type="pmc">BMJ</journal-id> <journal-id journal-id-type="publisher">BR MED J</journal-id> <issn>0959-8138</issn> <publisher> <publisher-name>British Medical Journal</publisher-name> </publisher> </journal-meta> <article-meta> <article-id pub-id-type="pmid">10092260</article-id> <title-group> <article-title>Systematic review of day hospital care for elderly people</article-title> </title-group> <contrib-group>...</contrib-group> <aff id="StLukes">...</aff> <pub-date pub-type="pub">...</pub-date> ... </article-meta> </front> ...