Securities of the U.S. government issued exclusively to the Old Age, Survivors, and Disability Insurance (OASDI); Disability Insurance (DI); Health Insurance (HI); and Supplementary Medical Insurance (SMI) trust funds and other federal trust funds. Section 1841(a) of the Social Security Act provides that the public-debt obligations issued for purchase by the SMI trust fund shall have maturities fixed with due regard for the needs of the funds. The usual practice in the past has been to spread the holdings of special issues, as of every June 30, so that the amounts maturing in each of the next 15 years are approximately equal. Special public-debt obligations are redeemable at par at any time.

Document that gives the details of an unusual or infrequently performed medical procedure and supports the necessity for providing services. It is submitted with an insurance claim.

Medical doctor who has received training in a specific area of medicine and who treats only certain parts of the body, certain health problems, or certain age groups such as cardiovascular surgeon, dermatologist, and endocrinologist. These doctors are board certified by doing additional advanced residency training followed by several years of practice in the specialty and then passing a specialty board examination. Members of managed care plans usually need approval from their primary care physician to see a specialist.

System of payment used by a managed care plan in which a specialist provider is paid a fixed, capitated fee for giving medical services.

Health care services that a medical specialist provides (e.g., cardiologist, dermatologist, orthopedic surgeon).

Flat fee paid to a medical specialist for all medical services or procedures.

Medicare contractor who performs a limited Medicare function such as coordination of benefits and statistical analysis.

Medical facility that provides health care services for specific illnesses or diseases (e.g., psychiatric hospital, rehabilitation hospital, long-term care hospital [LTCH]).