ISSA
Inter-service support agreement (ISSA) means any agreement between two or more executive agencies (including the Department of Defense) in which one agency consents to perform aviation support services (e.g., providing an aircraft and other aviation services or providing only services) for another agency with or without cost-reimbursement. An executive agency-to-executive agency agreement that involves only the use of an aircraft, not services, is a bailment, not an ISSA.