Editing Digital object identifier (section)

=={{anchor|Prefix|Suffix|DOI registrant}} Nomenclature and syntax==
A DOI is a type of Handle System handle, which takes the form of a [[string (computer science)|character string]] divided into two parts, a prefix and a suffix, separated by a slash.
 prefix/suffix

The prefix identifies the registrant of the identifier and the suffix is chosen by the registrant and identifies the specific object associated with that DOI. Most legal [[Unicode]] characters are allowed in these strings, which are interpreted in a [[case-insensitive]] manner. The prefix usually takes the form <code>10.NNNN</code>, where <code>NNNN</code> is a number greater than or equal to <code>1000</code>, whose limit depends only on the total number of registrants.<ref name="CrossRefDOI">{{cite web |title=doi info & guidelines |date=2013 |publisher=Publishers International Linking Association, Inc. |website=CrossRef.org |url=http://www.crossref.org/01company/15doi_info.html |access-date=10 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20021021021703/http://www.crossref.org/01company/15doi_info.html |archive-date=2002-10-21 |quote=All DOI prefixes begin with "10" to distinguish the DOI from other implementations of the Handle System followed by a four-digit number or string (the prefix can be longer if necessary).}}</ref><ref name="DOIKeyFacts">{{cite web |title=Factsheet—Key Facts on Digital Object Identifier System |publisher=International DOI Foundation |date=6 June 2016 |url=https://www.doi.org/the-identifier/resources/factsheets/key-facts-on-digital-object-identifier-system |access-date=1 November 2024 |url-status=live |archive-url=https://web.archive.org/web/20160605202057/http://www.doi.org/factsheets/DOIKeyFacts.html |archive-date=5 June 2016 |quote=Over 18,000 DOI name prefixes within the DOI System}}</ref> The prefix may be further subdivided with periods, like <code>10.NNNN.N</code>.<ref name="2.2.2">{{cite web |title=DOI Handbook—2 Numbering |publisher=International DOI Foundation |date=1 February 2016 |url=https://doi.org/doi_handbook/2_Numbering.html#2.2.2 |access-date=10 June 2016 |url-status=deviated |archive-url=https://web.archive.org/web/20140630181440/http://www.doi.org/doi_handbook/2_Numbering.html#2.2.2 |archive-date=30 June 2014 |quote=The registrant code may be further divided into sub-elements for administrative convenience if desired. Each sub-element of the registrant code shall be preceded by a full stop.}}</ref>

For example, in the DOI name <code>10.1000/182</code>, the prefix is <code>10.1000</code> and the suffix is <code>182</code>. The "10" part of the prefix distinguishes the handle as part of the DOI namespace, as opposed to some other Handle System namespace,{{efn-ua|Other registries are identified by other strings at the start of the prefix.}} and the characters <code>1000</code> in the prefix identify the registrant; in this case the registrant is the International DOI Foundation itself. <code>182</code> is the suffix, or item ID, identifying a single object (in this case, the latest version of the ''DOI Handbook'').

DOI names can identify creative works (such as texts, images, audio or video items, and software) in both electronic and physical forms, [[performance]]s, and abstract works<ref name="doifaq2">{{cite web |title=Frequently asked questions about the DOI system: 6. What can a DOI name be assigned to? |date=3 July 2018 |website=DOI Foundation |url=https://www.doi.org/the-identifier/resources/faqs#8-what-can-a-doi-name-be-assigned-to |access-date=19 July 2018 |url-status=live |archive-url=https://web.archive.org/web/20230216162638/https://www.doi.org/the-identifier/resources/faqs#8-what-can-a-doi-name-be-assigned-to |archive-date=16 February 2023}}</ref> such as licenses, parties to a transaction, etc.

The names can refer to objects at varying levels of detail: thus DOI names can identify a journal, an individual issue of a journal, an individual article in the journal, or a single table in that article. The choice of level of detail is left to the assigner, but in the DOI system it must be declared as part of the metadata that is associated with a DOI name, using a [[data dictionary]] based on the [[indecs Content Model]].

===Display===
The official ''DOI Handbook'' explicitly states that DOIs should be displayed on screens and in print in the format <code>doi:10.1000/182</code>.<ref name="C4WDefault-2811140">{{cite web |title=DOI Handbook – Numbering |date=13 February 2014 |website=doi.org |author1=<!--Staff writer(s); no by-line.--> |at=Section 2.6.1 Screen and print presentation |url=https://doi.org/doi_handbook/2_Numbering.html#2.6.1 |access-date=30 June 2014 |url-status=live |archive-url=https://web.archive.org/web/20140630181440/http://www.doi.org/doi_handbook/2_Numbering.html |archive-date=30 June 2014}}</ref>

Contrary to the ''DOI Handbook'', [[Crossref]], a major DOI registration agency, recommends displaying a URL (for example, <code><nowiki>https://doi.org/10.1000/182</nowiki></code>) instead of the officially specified format.<ref>{{cite web |title=DOI Display Guidelines |url=http://www.crossref.org/02publishers/doi_display_guidelines.html |access-date=19 October 2016 |url-status=live |archive-url=https://web.archive.org/web/20161124110844/http://www.crossref.org/02publishers/doi_display_guidelines.html |archive-date=24 November 2016}}</ref><ref>{{cite web |title=New Crossref DOI display guidelines are on the way |url=http://blog.crossref.org/2016/09/new-crossref-doi-display-guidelines.html |access-date=19 October 2016 |url-status=live |archive-url=https://web.archive.org/web/20161019215501/http://blog.crossref.org/2016/09/new-crossref-doi-display-guidelines.html |archive-date=19 October 2016}}</ref> This URL is persistent (there is a contract that ensures persistence in the doi.org domain,{{Citation needed|date=September 2024}}) so it is a [[PURL]]—providing the location of an [[name server|name resolver]] which will redirect [[HTTP request]]s to the correct online location of the linked item.<ref name="dd"/><ref>{{cite journal |last=Powell |first=Andy |title=Resolving DOI Based URNs Using Squid: An Experimental System at UKOLN |journal=D-Lib Magazine |date=June 1998 |issn=1082-9873 |doi=10.1045/june98-powell |doi-access=free |url=http://www.dlib.org/dlib/june98/06powell.html |access-date=23 April 2010 |url-status=live |archive-url=https://web.archive.org/web/20100613000342/http://dlib.org/dlib/june98/06powell.html |archive-date=13 June 2010}}</ref>

The Crossref recommendation is primarily based on the assumption that the DOI is being displayed without being hyperlinked to its appropriate URL—the argument being that without the hyperlink it is not as easy to copy-and-paste the full URL to actually bring up the page for the DOI, thus the entire URL should be displayed, allowing people viewing the page containing the DOI to copy-and-paste the URL, by hand, into a new window/tab in their [[Web browser|browser]] in order to go to the appropriate page for the document the DOI represents.<ref>{{cite web |title=Crossref Revises DOI Display Guidelines - Crossref |last=ChrissieCW |website=crossref.org |url=https://www.crossref.org/news/2011-08-02-crossref-revises-doi-display-guidelines/ |access-date=25 April 2018 |url-status=live |archive-url=https://web.archive.org/web/20180425114838/https://www.crossref.org/news/2011-08-02-crossref-revises-doi-display-guidelines/ |archive-date=25 April 2018}}</ref>