Section 1. In this chapter the following words shall have the following meanings:

''Certified nurse midwife'', a nurse midwife authorized to practice midwifery in the commonwealth by the board of registration in nursing pursuant to section eighty B of chapter one hundred and twelve.

''Commissioner'', the commissioner of insurance.

''Covered dependent'', a dependent for whose medical or chiropractic care provision is made in a subscription certificate issued by a medical service corporation to a subscriber.

''Dependent'', the spouse, child or foster child of a subscriber, or an adult relative dependent upon the subscriber for his support.

''Medical service'', the medical services ordinarily provided by registered physicians in accordance with accepted practices in the community where the services are rendered.

''Chiropractic service'', the chiropractic services ordinarily provided by registered chiropractors in accordance with accepted practices in the community where the services are rendered.

''Visual service'', the optometric services ordinarily provided by registered optometrists and physicians in accordance with accepted practices in the community where the services are rendered.

''Medical service corporation'', a corporation organized as provided by this chapter for the purpose of establishing and operating a non-profit medical service plan.

''Nonparticipating provider'', a registered physician under the provisions of chapter one hundred and twelve or other provider of health care services licensed under the laws of the commonwealth who is not party to an agreement in writing with a medical service corporation to perform medical services for subscribers and covered dependents who are covered under a preferred provider arrangement approved by the commissioner under chapter one hundred and seventy-six I.

''Nonprofit medical service plan'', a plan operated by a medical service corporation under the provisions of this chapter, whereby the cost of medical and chiropractic services and other health services furnished to subscribers and covered dependents is paid by the corporation, to participating physicians, to participating chiropractors, to nonparticipating providers if the subscriber is covered by a Preferred Provider Organization, and to such other physicians as are provided for herein, and to providers of other health services.

''Participating nurse midwife'', a certified nurse midwife who agrees in writing with a medical service corporation to perform midwifery service for subscribers and covered dependents and to abide by the by-laws, rules and regulations of such corporation.

''Participating physician'', a registered physician under the provisions of chapter one hundred and twelve who agrees in writing with a medical service corporation to perform medical service for subscribers and covered dependents and to abide by the by-laws, rules and regulations of such corporation.

''Participating chiropractor'', a registered chiropractor under the provisions of chapter one hundred and twelve who agrees in writing with a medical service corporation to perform chiropractic service for subscribers and covered dependents and to abide by the by-laws, rules and regulations of such corporation.

''Participating optometrist'', a registered optometrist who agrees in writing with a medical service corporation to perform visual service for subscribers and covered dependents and to abide by the by-laws, rules and regulation of such corporation.

''Primary care provider'', a health care professional qualified to provide general medical care for common health care problems who; (1) supervises, coordinates, prescribes, or otherwise provides or proposes health care services; (2) initiates referrals for specialist care; and (3) maintains continuity of care within the scope of practice.

''Registered physician'', a physician registered to practice medicine in the commonwealth as provided in section two of chapter one hundred and twelve.

''Registered chiropractor'', a chiropractor registered to practice chiropractic in the commonwealth as provided in section eighty-nine of chapter one hundred and twelve.

''Subscriber'', a person who has subscribed to a non-profit medical service plan and to whom a subscription certificate has been issued in accordance with the provisions of section six.