This National Standard of Canada is equivalent to International Standard ISO/TS 21091:2005. 1 Scope This Technical Specification defines minimal specifications for directory services for health care using the X.500 framework. This Technical Specification provides the common directory information and services needed to support the secure exchange of health care information over public networks. This Technical Specification addresses the health directory from a community perspective in anticipation of supporting interenterprise, inter-jurisdiction, and international health care communications. Besides technical security measures that are discussed in other ISO standards, communication of health care data requires a reliable accountable "chain of trust." In order to maintain this chain of trust within a public key infrastructure, users (relying parties) must be able to obtain current correct certificates and certificate status information through secure directory management. In addition to the support of security services such as access control and confidentiality, a standard shall provide specification for other aspects of communication, such as addresses and protocols of communication entities. This Technical Specification also supports directory services aiming to support identification of health professionals and organizations and the patients/consumers. The latter services include aspects sometimes referred to as master patient indices. The health care directory will only support standard LDAP Client searches. Specific implementation guidance, search criteria and support are out of scope of this document.