<object-id> Object Identifier

Unique identifier (such as a DOI or URI) for a component within an article (for example, for a figure or a table).


The <object-id> element holds an external identifier, typically assigned to an object such as a table by a publisher. As such, these elements are expected to be rare in Authoring, but they are allowed, in case the author wants to register DOIs or similar. An element, rather than an attribute, was chosen to hold these DOIs and other identifiers so that multiple identifiers could be described.
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 perform a simple link inside the document.

Attribute Best Practice

Type of Identifier

While the values of the @object-id-type attribute are unconstrained, Best Practice is to use it to indicate the type of the external identifier, such as a publisher’s identifier, a DOI, a PMID, an aggregator’s or archive’s identifier, the identifier assigned by an indexing or hosting service, or similar.

Authority for Identifier

The attribute @assigning-authority should name the organization or system that assigned the identifier or administers the identifier (such as Crossref, OCLC, GenBank, Figshare).
Recording a DOI — Publication Identifier versus an Object Identifier
This tag set includes two elements which may be used to record a DOI as an identifier:
  • The <pub-id> element is used inside a citation (and similar elements such as <product>) to provide an identifier such as a DOI for a cited publication.
  • The <object-id> (used on many elements within the document as well as inside citations) is used to identify parts of an article. For example, a particular table, figure, ref-list, or table in the narrative text may be given an <object-id> such as a DOI so that it can be referenced. Similarly, an <object-id> inside a citation is the identifier of the citation, so that it can be referenced; it is not an identifier for the cited object.
Consequently, a bibliographic reference (<element-citation> or <mixed-citation>) could contain both the <object-id> element (with the DOI for that citation) and the <pub-id> element (with the DOI for the article being referenced in the citation).

Base Attributes

Models and Context
May be contained in
Text, numbers, or special characters
Content Model
<!ELEMENT  object-id    (#PCDATA)                                    >
Tagged Sample

Media object

<media id="v1" mime-subtype="avi" mimetype="video" orientation="portrait" 
  position="anchor" specific-use="original-format" xlink:href="v1-video1-orig.avi">
 <object-id pub-id-type="doi" specific-use="metadata">10.1063/1.4807071.1</object-id>