A document that regulates the security-related aspects of a planned relationship between an organization and an external system. It regulates the security interface between two systems operating under two different authorities. It contains a variety of descriptive, technical, process engineering and planning information. It is usually preceded by a formal Memorandum of Understanding/Understanding that defines general roles and responsibilities in managing a cross-domain connection. Source(s): SCISS 4009-2015 In this guide, an agreement has been reached between organizations that own and operate networked IT systems to document the technical requirements of the connection. IAPH also supports a Memorandum of Understanding (MOU/A) between organizations. Source(s): NIST SP 800-47 under the Interconnection Security Agreement (ISA) Comments on specific definitions should be sent to the authors of the linked source publication. For NIST publications, there is usually an email inside the document. Comments on the presentation and functionality of the glossary should be addressed to firstname.lastname@example.org. .