Editing Identifier (section)

===Identifiers (IDs) versus Unique identifiers (UIDs)===
{{Main|Unique identifier}}
A resource may carry multiple identifiers. Typical examples are:
* One person with multiple names, nicknames, and forms of address (titles, salutations)
** ''For example:'' One specific person may be identified by all of the following identifiers: Jane&nbsp;Smith; Jane&nbsp;Elizabeth&nbsp;Meredith&nbsp;Smith; Jane&nbsp;E.&nbsp;M.&nbsp;Smith; Jane&nbsp;E.&nbsp;Smith; Janie&nbsp;Smith; Janie; Little&nbsp;Janie (as opposed to her mother or sister or cousin, Big&nbsp;Janie); Aunt&nbsp;Jane; Auntie&nbsp;Janie; Mom; Grandmom; Nana; Kelly's&nbsp;mother; Billy's&nbsp;grandmother; Ms.&nbsp;Smith; Dr.&nbsp;Smith; Jane&nbsp;E.&nbsp;Smith,&nbsp;PhD; and Fuzzy (her jocular nickname at work).
* One document with multiple versions<ref name=paid>{{cite web
  | last = University of Glasgow
  | author-link = University of Glasgow
  | title = Procedure for Applying Identifiers to Documents
  | url = http://www.gla.ac.uk/infostrat/ERM/Docs/procref.htm
  | access-date = 28 April 2009
  | archive-url = https://web.archive.org/web/20110605081415/http://www.gla.ac.uk/infostrat/ERM/Docs/procref.htm
  | archive-date = 5 June 2011
  | url-status = dead
  }}</ref>
* One substance with multiple names (for example, [[Chemical Abstracts Service|CAS]] index names versus [[IUPAC]] names;<ref name=icn>{{cite web
  | last = University of Pennsylvania
  | author-link = University of Pennsylvania
  | title = Information on Chemical Nomenclature
  | url = http://gethelp.library.upenn.edu/guides/scitech/chemnom.html
  | access-date = 28 April 2009
  | archive-date = 4 January 2009
  | archive-url = https://web.archive.org/web/20090104023819/http://gethelp.library.upenn.edu/guides/scitech/chemnom.html
  | url-status = dead
  }}</ref> [[International Nonproprietary Name|INN]] generic drug names versus [[United States Adopted Name|USAN]] generic drug names versus brand names)

The inverse is also possible, where multiple resources are represented with the same identifier (discussed below).