!!! Overview
[{$pagename}] are [Identifiers] or [attributes] or [properties|Property] of an [Entity] (or [Digital Identity] or even a [Digital Subject]) that provide [Identification] of the [entity]


[{$pagename}] should be [Attributes] that within the current [context] can be used to separate the [entity] from the [Anonymity Set] ([Identification]) a specific [Digital Identity]. 
Otherwise, they are just [Attributes].


!! [Examples]
The [Natural Person] (i.e. [Entity]) [Bob] Smith might be represented as a [Digital Subject] in the [Context] of his [employer], the Port Control Authority. This [Digital Subject] might have the following types of [{$pagename}] (and associated values) in this context:[1]
* [Email Address] = bob@portcontroll.gov
* [Phone Number] = 617-555-1234
* [passport] information = ...etc.
* [Fingerprint] data = ...etc. 

This same [Entity] [Bob] Smith is also represented as a [Digital Identity] in a "customer-to-Clothes-R-Us" Context (this customer's [relationship] with the Clothes-R-Us merchant. In this [Context] Bob has these [Attributes]:
* platinumCustomer - Is probably a [{$pagename}] and classified as a [Unidirectional identifier]
* [EmployeeNumber] - Is a [{$pagename}] and classified as a [Unidirectional identifier]
* preferredColor = "blue" - By itself is not a [{$pagename}] as there can be no [Identification] of [Bob] 
* shirtSize = L - By itself is not a [{$pagename}] as there can be no [Identification] of [Bob] 
* streetNumber - By itself is not a [{$pagename}] as there can be no [Identification] of [Bob] 
* [Last Name] - By itself is not a [{$pagename}] as there can be no [Identification] of [Bob] 
However, if we use [Identity Correlation] of preferredColor and shirtSize and streetNumber and [Last Name] we may have only one [Digital Identity] in the result. In some [Contexts] these attributes may be considered [Identity Attributes] ([HIPAA]'s [Protected Health Information])

!! In Higgins[2]
! Types
In Higgins a [{$pagename}] is identified by a [URI] that defines its type. The URI 
{{{http://openschemas.org/2006/person/surname }}}
might indicate an Identity Attribute that represented a person's [Last Name]. The [schema] associated with the containing [Context] provides metadata about this [URI].

! Values
* An [{$pagename}] may have zero or more values
* The values may be literal types (defined by the [XML] Schema literal types) or complex (structured) values
* A special kind of [{$pagename}] is called a [Subject Relationship] whose value is a reference to another [Digital Subject] in the same or a different [Context]
* Some [{$pagename}] are defined by the containing [Context]'s schema to allow multiple unique values. For example the attribute preferredBreakfast
** might have the values {spam, eggs}, 
** but it could not have the values {spam, spam, spam, eggs, spam}. 

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }] 
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* [#1] - [Identity Attribute|http://wiki.idcommons.net/Identity_Attribute|target='_blank'] - based on information observed on 2014-08-21