!!! Overview[1]
[{$pagename}] [{$pagename}] is a [NamingContext], in [Microsoft Active Directory], Contains the [Schema] container, which stores [ObjectClass Types] and [Attribute Types] definitions for all existing and possible [Microsoft Active Directory] objects in cn=schema,cn=configuration,dc=[Forest Root Domain]. [{$pagename}] is [replica] is held by all [Domain Controllers] in the [AD Forest] and there is __only one__ [{$pagename}] per [AD Forest] 

You can view the contents of the [{$pagename}] in the Active Directory Schema console.[{$pagename}] is part of the [Directory Partition Hierarchy] within [Microsoft Active Directory][{$pagename}] is writable, [schema] updates are allowed on only the [Domain Controller] that holds the role of [Schema Master FSMO Role].

!! More Information
There might be more information for this subject on one of the following:
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* [#1] - [Directory Partitions|https://technet.microsoft.com/en-us/library/cc961591.aspx|target='_blank'] - based on information obtained 2016-09-25