Every single LDAP entry has a special attribute called objectClass that defines what type of object(s) the entry represents. For example, the such object classes as person and organizationalPerson may well serve as a description of what kind of information an LDAP entry actually contains.
The objectClass attribute determines, which attributes an entry must or may have, meaning that one won't be able to either add or remove values to the objectClass attribute because of a risk of getting the Object Class Violation error.
Suppose you want to remove the person object class from your entry. This object class forces an entry to contain both the cn and sn attributes. If you just remove the person object class, the entry will no longer comply with the schema due to still having ineligible (i.e. defined by no object class whatsoever) cn and sn attributes.
Likewise, if you wish to add the person object class to an entry, you can't just add the 'person' value to the objectClass attribute because an entry already having this object class must, by default, contain the cn and sn attributes. To resolve this sort of issues, LDAP Administrator provides the Add or Remove Object Classes Wizard.
To add or remove object classes from an entry:
Select an entry whose structure you wish to modify.
Click
Add or Remove Object Classes on the Entry toolbar.
The Add or Remove Object Classes Wizard comprises two steps:
Step 1: Object Classes SelectionAt this step you can add some new or remove existing object classes from an entry. To add an object class to the entry being modified, select one in the Available object classes list and click the >> button, double-click or just press Space. To remove an object class from the entry, select it in the Selected object classes list and click <<, or double-click it. You can also drag-and-drop object classes to move them between the lists.
If your intention was just to remove some object classes without adding new ones, click Finish to confirm and to close the wizard.
Step 2: Specifying Values for New AttributesHere you'll be offered to specify values for attributes belonging to the newly added object classes. Required attributes that must necessarily be present in the entry, are marked in bold.
Add and remove attributes. You can add an attribute to an entry by clicking the Add Attribute button and then choosing a name for it from the offered list of names. This list contains all the attributes available as specified by the LDAP schema, but only those not already present in the entry. To remove an attribute, select either it or one of its values and click Remove Attribute or press Del.
Add and remove attribute values. To add an attribute value, select the whole attribute or one of its values and click Add Value or press Ins. Please note: a value will only be added to an attribute provided it does not have any empty values. If it does, the application will ask to enter or remove such value. To remove an attribute value, select it and click Remove Value or press Shift+Del.