Many different, but similar, definitions exist for IDS. IDS, as an entity, does not have to abide by strict regulations, as does an HMO. When an IDS offers a health plan, however, it must then abide by the requirements of the state and federal government for health plans, insurance companies or HMOs. Without owning a health plan product, an IDS will usually abide by the regulations that govern its separate businesses, that is, regulations governing hospitals, clinics and physicians. An IDS can be a financial or contractual arrangement between health providers (usually hospitals and doctors) to offer a comprehensive range of health care services through a separate legal entity operating, at least for these purposes, as a single health care delivery system. IDS can be a network of organizations usually including hospitals and physician groups, that provides or arranges to provide a coordinated continuum of services to a defined population and is held both clinically and fiscally accountable for the outcomes of the populations served. IDS can also be a healthcare provider organization which vertically integrates physician, hospital, and, usually, also health plan businesses in some manner in order to establish a full continuum of care, seamless of delivery of services and the ability to manage care under new reimbursement arrangements. Also called delivery system, vertically integrated system, horizontally integrated system, health delivery network, accountable health plan, and other names.