I am trying to set up an external LDAP filter for GAL in Zimbra, does anyone know what the variable substitution in the filter for the search item would be?

ie. (|(cn=%s)(sn=%s))

the %s would be my search term that I am looking for, any idea what this would be for the filter in the admin? I have tried %s and it doesn't work, and I cannot find any documentation on the variables anywhere.