SEARCHBASE is the Distinguished Name (DN) of the object.
DELIMITER is the value of the LDAP config AM group delimiter property.
FILTER is the LDAP or Active Directory attribute filter.
When you are using group based synchronization, FILTER is optional: if omitted, the Marketing Platform server dynamically creates the filter based on the value of the LDAP user reference attribute name property.
When you are using attribute based synchronization, users are additionally filtered based on attributes you set in the FILTER portion of the value. Set the FILTER to the attribute on which you want to search. To specify a filter using multiple attributes, use LDAP search filter syntax. For example, if you want to import all users with c=France, and you also want to import users with department=marketing regardless of the c value of these users, the setting would be similar to the following.