158. Projects' selection of a directory product is usually dictated by their choice of messaging product (e.g. Microsoft Exchange requires the use of Active Directory in order to provide a messaging service). However, X.500-compliant products (as required by NATO) are commercially available, and are becoming more de-coupled from the messaging service. Meta-directories now offer a viable solution to the integration of different directory products. LDAP v3 is the internationally accepted access protocol supported by all vendors.