!!! Overview
[{$pagename}] is a very important part of [LDAP] directory services. 

[{$pagename}] is defined in [RFC 4512].

!! Schema Definitions
Schema definitions in this section are described using [ABNF] and rely on the common productions specified in Section 1.2 as well as these:
%%prettify 
{{{
noidlen = numericoid [ LCURLY len RCURLY ]
len = number

oids = oid / ( LPAREN WSP oidlist WSP RPAREN )
oidlist = oid *( WSP DOLLAR WSP oid )

extensions = *( SP xstring SP qdstrings )
xstring = "X" HYPHEN 1*( ALPHA / HYPHEN / USCORE )

qdescrs = qdescr / ( LPAREN WSP qdescrlist WSP RPAREN )
qdescrlist = [ qdescr *( SP qdescr ) ]
qdescr = SQUOTE descr SQUOTE

qdstrings = qdstring / ( LPAREN WSP qdstringlist WSP RPAREN )
qdstringlist = [ qdstring *( SP qdstring ) ]
qdstring = SQUOTE dstring SQUOTE
dstring = 1*( QS / QQ / QUTF8 )   ; escaped UTF-8 string

QQ =  ESC %x32 %x37 ; "\27"
QS =  ESC %x35 ( %x43 / %x63 ) ; "\5C" / "\5c"

; Any UTF-8 encoded Unicode character
; except %x27 ("\'") and %x5C ("\")
QUTF8    = QUTF1 / UTFMB

; Any ASCII character except %x27 ("\'") and %x5C ("\")
QUTF1    = %x00-26 / %x28-5B / %x5D-7F
}}} 
/%
Schema definitions in this section also share a number of common terms.
* The [NAME] field provides a set of short names ([LDAP Descriptors]) that are to be used as aliases for the OID.
* The [DESC] field optionally allows a descriptive string to be provided by the directory administrator and/or implementor.  While specifications may suggest a descriptive string, there is no requirement that the suggested (or any) descriptive string be used.
* The [OBSOLETE] field, if present, indicates the element is not active.
Implementers should note that future versions of this document may expand these definitions to include additional terms.  Terms whose identifier begins with "X-" are reserved for private experiments and are followed by <SP> and <qdstrings> tokens.


Although many people may have a basic understanding of [attribute Types] and [objectClass Types], there is a great deal of information about [{$pagename}] that most people do not know. 

Because [{$pagename}] is important it is extremely useful to have a more complete understanding of what it really entails. We will make further attempts to provide an in-depth description of schema elements in general.

[{$pagename}] of a [Directory System Agent] defines a set of rules that govern the kinds of [data] that the server can hold. [{$pagename}] is comprised of a number of different [LDAP Schema Element Types]

[Attributes|Attribute] are the elements responsible for storing [data] in a directory, and the [{$pagename}] defines the rules for which [AttributeTypes] may be used in an [LDAP Entry], the kinds of values that those [AttributeTypes] may have, and how [DUA] may interact with those [Attribute Values].

[DUA] may learn about the [{$pagename}] elements that the server supports by retrieving an appropriate [SubschemaSubentry].


!! A collection of Links On [{$pagename}]
* [LDAP Query For Schema]
* [PAM LDAP Schema Modifications|PAMSchemaModifications]
* [EDirectory Schema Reference]
** [LDAP Schema for NDS]
* [LDAP Schema Viewer|http://ldap.akbkhome.com/index.php]
* [SUN LDAP Schema Tutorial|http://java.sun.com/products/jndi/tutorial/ldap/schema/index.html]
* [Schema Extensions]
* [Make Changes to the Existing Schema|LDIF Schema Modifications]
* [Overview of Schema Modifications|Schema Modifications]
* [Edirectory's Location of the RFC-2307 Schema|RFC2307Schema]
* [Schema Browser Tool|SchemaBrowserTool]
* The [Willeke Schema]
* [SubschemaSubentry]
* [The COSINE and Internet X.500 Schema]
* [Microsoft Active Directory Attributes]
* [Microsoft Active Directory Syntax]
!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]