!!! Overview
[{$pagename}] is a [Number] specified in [AttributeSchema] for [Microsoft Active Directory] which indicated a [Linked Attribute][{$pagename}] [Attribute Values] indicate:
* Even [Attribute Value] are [forward links] 
* Odd [Attribute Value] are [BackLinks] equals to the [{$pagename}] of the corresponding [forward link] [{$pagename}] plus one.
* [Attribute Value] of 0 or not present implies it is NOT a [Linked Attribute]

[Forward links] (or [Forward Reference]) [attributes] always have a __even value__ [{$pagename}] and for every [Forward link] the next [{$pagename}] value is, of course, an __odd value__ and is the [{$pagename}] to the corresponding [BackLink] attribute.

!! [LDAP] ([Microsoft Active Directory]) [Attribute] Definition
The [{$pagename}] [AttributeTypes] is defined as:
* [CN|Cn]: 
* [OID] of [1.2.840.113556.1.2.50] 
* [NAME|Attribute-Name]: [{$pagename}]
* [DESC]: attribute specifies an integer that indicates that the attribute is a [Linked Attribute]. An even integer is a [forward link ]and an odd integer is a [BackLink].
* [EQUALITY]: []
* [ORDERING]: []
* [SYNTAX]: [2.5.5.9]
* [LOWERBOUND]:
* [UPPERBOUND]: 
* [OMSyntax]: 2
* [SchemaIDGUID]: [bf96799b-0de6-11d0-a285-00aa003049e2]
* [mapiID]: 32965
* [SINGLE-VALUE]
* [NO-USER-MODIFICATION]
* [USAGE]: [OperationalAttribute] 
* [Extended Flags]: 
** [X-ORIGIN]: []
* [X-SYSTEMFLAGS]
** [FLAG_SCHEMA_BASE_OBJECT]
* [X-SCHEMAFLAGSEx]
** [FLAG_ATTR_IS_CRITICAL]
* [X-SEARCH-FLAGS]
* Used as [MUST] in:
** 
* Used as [MAY] in:
**

!! Auto-Generated [{$pagename}] on [LDAP] [Add Request]
If the [DomainControllerFunctionality] is [Windows Server 2003] or greater, and an [attributeSchema] object is created with LDAP Add, and the Add request assigns the [OID] [1.2.840.113556.1.2.50] as the [Attribute Value] of the [{$pagename}] attribute, the [DC] sets the linkID attribute to an even integer that does not already appear as the linkID on a schema object. The attribute created by the Add is a [Forward link] attribute.

If the [LDAP] [Add Request], assigns either the attributeID or the lDAPDisplayName of an existing [forward link] attribute as the value of the linkID attribute, the [DC] sets the linkID attribute to the [{$pagename}] of the given __[forward link] attribute plus one__. The attribute created by the Add is a [BackLink] attribute corresponding to the given [forward link] attribute.

The aforementioned values that trigger auto-generation behavior for the linkID are of syntax String(Object-Identifier) or String([Unicode]), and therefore __do not conform to the declared syntax__ of the [{$pagename}] attribute. The DC accepts these values without the error that would normally occur in such a case.

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
----
* [#1] - [3.1.1.2.3 Attributes|https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-adts/cf133d47-b358-4add-81d3-15ea1cff9cd9|target='_blank'] - based on information obtained 2020-02-16 
* [#2] - [3.1.1.2.3.1 Auto-Generated linkID|https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-adts/3c44bae8-c09a-439e-b266-6ffc7835d52d|target='_blank'] - based on information obtained 2020-02-16