Linked attributes are pairs of attributes in which the system calculates the values of one attribute (the back link) based on the values set on the other attribute (the forward link) throughout the forest. A back-link value on any object instance consists of the DNs of all the objects that have the object's DN set in the corresponding forward link. For example, "Manager" and "Reports" are a pair of linked attributes, where Manager is the forward link and Reports is the back link. Now suppose Bill is Joe's manager. If you store the DN of Bill's user object in the "Manager" attribute of Joe's user object, then the DN of Joe's user object will show up in the "Reports" attribute of Bill's user object.
A forward link/back link pair is identified by the linkID values of two attributeSchema definitions. The linkID of the forward link is an even, positive, nonzero value, and the linkID of the associated back link is the forward linkID plus one. For example, the linkID for "Manager" is 42 and the linkID for "Reports" is 43.
The following is a list of guidelines for defining a new pair of linked attributes: