Many if not all artifacts, which have been valued enough to have been described and defined for Public disclosure, can receive this classification or category: ItsAnId

But
* The term Id, can mean many thing to many people, while meaning something very specific to others.
** Over 200 Acronyms - http://www.acronymfinder.com/ID.html
* In a database, the Key, is to be a UniqueId, in its Context of being in a Table.
* Some Ids bear the responsibility of defining or grouping of stuff into classes, as in AnimalVegetableMineral.
* The following have been used:
** User Id - to identify a personality usually with password to make unique as a user of a system or site
** Last four on front or three digits on the reverse of card as well as name, billing address, date of expiration and multiple digit number account number on a credit or debit card, used to verify a customer's identity
** Almost all Computing Artifacts bear a name specifying their identity

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See
* MeaningfulName
* SystemOfNames
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CategoryClassification