You can use the following virtual properties:
adm-InitiatorUserName (alias: initiator) - the logon name of the user, who performed the operation that resulted in the property resolve. For example, this property can be used to insert information about the user, who created objects. If you specify the following pattern Created by: %initiator% for the Description property via a Business Rule, description of new objects will contain logon names of users who created these objects ('Created by: johndoe@company.com').
adm-InitiatorDN - the DN of the operation initiator.
adm-InitiatorSid - the SID of the operation initiator.
adm-InitiatorParentDN - the DN of the OU/container, where the operation initiator is located.
For more information on virtual (or calculated) properties and value references, see Value Reference Format.