LDAP schema are made of of two main components: attributes and object classes. Once an attribute is defined, it can be used in any number of object classes. An object class tells the LDAP server which attributes are required and which are optional for a given entry. objectClass is also an attribute, and each LDAP entry has to declare at least one objectClass.
Please see the EDS Attributes page for details about all of the attributes used in the EDS.
Please see the EDS ObjectClasses page for details about all of the object classes used in the EDS.