[136]*136GILLETTE, J.
Petitioner brought an original proceeding in the Court of Appeals challenging the validity of an administrative rule promulgated by the Workers’ Compensation Department (the department).1 The rule limits the circumstances under which an insurer or a self-insured employer may be required to reimburse a nurse practitioner2 who provides medical services relating to a compensable illness or injury. OAR 436-10-050(4).3 Petitioner argues that a nurse practitioner is a “doctor or physician” as those terms are defined by statute and [137]*137that the department exceeded its authority in restricting reimbursement for nurse practitioners. Alternatively, she argues that the challenged rule violates Article I, section 20, of the Oregon Constitution and the Fourteenth Amendment to the United States Constitution, because it unreasonably differentiates between nurse practitioners and physician’s assistants by imposing fewer restrictions on a physician’s assistant’s eligibility for reimbursement. We agree with the first argument.
The Court of Appeals initially upheld the rule without opinion. Cook v. Workers’ Compensation Department, 85 Or App 219, 736 P2d 230 (1987). On reconsideration, the court withdrew its decision because “[a] challenge to an administrative rule in this court is an original proceeding, and our determination of the rule’s validity should, generally, be by written opinion.” Cook v. Workers’ Compensation Department, 87 Or App 486, 487, 742 P2d 714 (1987). The court again upheld the challenged rule, stating that “[w]e have considered petitioner’s arguments challenging the validity of OAR 436-10-050 and find them to be without merit.” Id. This court allowed review. We find that the department misinterpreted the pertinent provision of law and, therefore, exceeded its authority in promulgating the challenged rule. Accordingly, we reverse the Court of Appeals.
We first consider petitioner’s argument that the [138]*138department lacked the statutory authority to promulgate the challenged rule. See Planned Parenthood Assn v. Dept. of Human Res., 297 Or 562, 565, 687 P2d 785 (1984). The director of the Workers’ Compensation Department is vested with the general authority to promulgate rules “which are reasonably required in the performance of the director’s duties” of administering, regulating and enforcing the workers’ compensation laws. ORS 656.726(3)(a). The duty to administer the Workers’ Compensation Law requires that the director apply the statutes to individual factual situations. That process necessarily involves interpretation of statutory terms, either by rule or by order in a contested case. It follows that the director had the authority to promulgate a rule interpreting the meaning of the statutory terms “doctor or physician.” The question remains — was that interpretation correct?
For the purposes of the Workers’ Compensation Law, the legislature has defined a “doctor or physician” as:
“[A] person duly licensed to practice one or more of the healing arts in this state within the limits of the license of the licentiate. ‘Attending physician’ means a doctor or physician who is primarily responsible for the treatment of a worker’s compensable injury. ‘Consulting physician’ means a doctor or physician who examines a worker or the worker’s medical record to advise the attending physician regarding treatment of a worker’s compensable injury.” (Emphasis supplied.)
ORS 656.005(12). Although the department has the authority to interpret the statutory terms, “doctor or physician,” that interpretation must be consistent with the policy underlying the legislative enactment. An administrative agency may not, by its rules, amend, alter, enlarge or limit the terms of a statute. U. of O. Co-oper. v. Dept. of Rev., 273 Or 539, 550, 542 P2d 900 (1975). The question before this court is whether the department’s interpretation of the statutory language comports with the statutory intent. Springfield Education Assn. v. School Dist., 290 Or 217, 228, 621 P2d 547 (1980).
When OAR 436-10-050 originally was promulgated in 1982, it authorized reimbursement for nurse practitioners who practiced in areas defined by the State Health Planning and Development Agency as medically underserved. The rule thus recognized the special, hybrid status of the nurse practitioner, different both from a traditional nurse and a traditional doctor. In 1985, the rule was amended to delete that provision and [139]*139add a provision that treatment by a nurse practitioner for a disabling illness or injury would be reimbursable only if the patient were referred to the nurse practitioner by the attending physician. Exhibit C to the 1985 amendment explains the agency’s reasoning:
“There was considerable testimony from nurse practitioners regarding the proposed rule, and the testimony was unanimous in objecting to any limitation on nurse practitioners, be it geographical or scope of practice, or any limitation regarding the extent of an injury that they could treat and be reimbursed for by the system.
“The intent of the rule was to allow nurse practitioners to treat nondisabling injuries and treat disabling injuries only when the patients were referred by attending physicians who would remain attending physicians and were in control of the case. This would remove the geographic limitation and allow all adult nurse practitioners and family nurse practitioners to treat nondisabling injuries, but would not designate them as attending physicians and it is the opinion of the department that the definition is defined in the statute and the department cannot expand the definition. * * *.” (Emphasis added).
It is apparent that the department concluded that nurse practitioners did not qualify as “doctors or physicians” under the statutory definition and therefore declined to permit their designation as attending physicians.4 For the reasons that follow, we hold that the department was incorrect in so concluding and therefore erred in adopting a rule that excludes nurse practitioners from the statutory definitions of “physician” and “attending physician.”
For the purposes of the Workers’ Compensation Law, a “physician” or “doctor” is defined, in part, as a person “licensed to practice one or more of the healing arts.” ORS 656.005(12). The issue before this court turns on the meaning of the term, “healing arts.” No Oregon statute or Supreme Court opinion defines that term, nor (so far as we can determine) does it have any special and immutable meaning either [140]*140in medicine or in the law. Although the term is used in various contexts throughout the Oregon Revised Statutes, no clear meaning can be distilled from those provisions. Neither has our research with respect to other jurisdictions produced much help. What law we have been able to find is primarily statutory. A summary of laws from other jurisdictions appear in the Appendix.
The definition of “doctor or physician” in ORS 656.005(12) was added by the 1957 legislature and has not been amended. Or Laws 1957, ch 718, § 1. The definitions of “attending physician” and “consulting physician” were added in 1979. Or Laws 1979, ch 839, § 26. The legislative history does not include specific discussion of those definitions. Certainly, nothing in the legislative history demonstrates any legislative intent to limit the broad, generic meaning of the term, “healing arts.”
The department argues that, at the time the language defining “doctor or physician” was added to the Workers’ Compensation Law, the term, “healing arts,” was defined in ORS chapter 676, which dealt with the health professions generally. Former ORS 676.140 provided, in part:
“Each board licensing any person to practice any healing art in this state shall file with the Secretary of State a list of all persons licensed by such board to practice such healing art, together with the last known address of each of such persons.”
The department notes that a 1949 attorney general opinion responded to the Board of Nursing’s inquiry whether they were subject to the requirements of former ORS 676.140. The attorney general concluded that nursing was not a “healing art.” 24 Op Att’y Gen 287 (Or 1949). That conclusion was based on the predecessor to ORS 676.110, which then provided:
“Any person practicing any of the healing arts or the corrective art of optometry who uses the title ‘doctor’ or any contraction thereof, ‘clinic,’ ‘institute,’ ‘specialist’ or any other assumed or artificial name or title, in connection with his business or profession, on any written or printed matter, or in connection with any advertising, billboards, signs or professional notices, shall add after his name or after any such assumed or artificial names, one of the following respective designations:
[141]*141“(1) In the case of a person practicing chiropody, the word ‘chiropodist’;
“(2) In the case of a person practicing chiropractic, the word ‘chiropractor’ or the words ‘chiropractic physician’;
“(3) In the case of a person practicing dentistry, the word ‘dentist’ or the words ‘dental surgeon’;
“(4) In the case of a person practicing naturopathy, the word ‘naturopath’ or the words ‘naturopathic physician’;
“(5) In the case of a person practicing the corrective art of optometry, the word ‘optometrist’;
“(6) In the case of a person practicing osteopathy, the word ‘osteopath’ or [‘]osteopathic physician and surgeon’;
“(7) In the case of a person practicing medicine or surgery, the word ‘physician’ or the word ‘surgeon’ or the words ‘physician and surgeon’;
“(8) In the case of a person practicing veterinary medicine, the word ‘veterinarian.’ ”
OCLA § 54-151.
The attorney general’s opinion read the statute quoted above as an exclusive list of designations for practitioners of the healing arts. Because the statute did not refer to the practice of nursing, the attorney general concluded that nursing was not a “healing art” and, therefore, the Board of Nursing need not provide the secretary of state with a list of licensed nurses under the predecessor to former ORS 676.140. See also 33 Op Att’y Gen 294 (Or 1967) (limiting healing arts practitioners to those listed in ORS 676.110 for purposes of statute requiring that “the certificate of a person licensed in this state to practice any of the healing arts” accompany application for absentee ballot on grounds of physical disability).
The department relies on essentially the same reasoning as the two attorney general opinions cited above. It argues that, when the 1957 legislature used the term, “healing arts,” it intended the term to encompass only those professions listed in the former version of ORS 676.110. We disagree.
We first note that, in 1957, ORS 676.110 did not expressly purport to define all practitioners of the healing arts. It applied only to those practitioners of the healing arts
[142]*142“who use[d] the title ‘doctor’ * * *, ‘clinic,’ ‘institute,’ ‘specialist’ or any other assumed or artificial name or title, in connection with his business or profession, on any written or printed matter, or in connection with any advertising, billboards, signs or professional notices * * *.”
Second, even if ORS 676.110 were intended to be an exhaustive list of healing arts practitioners for the purpose of advertising regulation, there is no indication that the 1957 legislature intended to incorporate that list into its definition of “doctor or physician” in an entirely unrelated workers’ compensation provision.
The term “healing arts” is not a static concept, capable of only one definition, now and forever. Instead, it is an example of the familiar legislative penchant for using general terms like a bucket, allowing various concepts to fall in (or out) with the passage of time. What is a “healing art” may have differed between 1957 and today, just as, for example, the concept of “vehicle” changed between 1890 and the present. But the legislature need not constantly update each new addition to either class — the general terms are broad and flexible enough to adjust to changing circumstances. The question therefore is, do “nurse practitioners” do things that make them practitioners of the “healing arts”?
They do. Nurse practitioners are licensed to provide “primary health care,” which is defined as “holistic health care which the client receives at the first point of contact with the health care system and is continuous and comprehensive.” OAR 851-50-000(3)(k); (n). OAR 851-50-005(2) provides:
“The nurse practitioner is independently responsible and accountable for the continuous and comprehensive management of a broad range of personal health services, which may include:
“(a) Promotion and maintenance of health;
“(b) Prevention of illness and disability;
“(c) Management of health care during acute and chronic phases of illness;
“(d) Guidance and counseling for both individuals and families;
“(e) Consultation and/or collaboration with other health care providers and community resources;
[143]*143“(f) Referral to other health care providers and community resources.” (Emphasis supplied.)
Nurse practitioners also are eligible to apply for prescription privileges upon completion of an approved course of pharmacology. OAR 851-50-120; 851-50-125.
Absent any indication to the contrary, we assume that the legislature intended to give the term, “healing arts,” its literal meaning, unless to do so would be so contrary to the statutory policy that it would bring about an absurd result. Johnson v. Star Machinery Co., 270 Or 694, 703-4, 530 P2d 53 (1974). “Healing” is generally defined as “curative.” See, e.g., Webster’s Third New International Dictionary (1971). A “healing art” would be commonly understood as the skill to treat disease or disability and, where the nature of the problem permits, to restore health. A nurse practitioner is qualified to provide comprehensive, independent medical care in the form of diagnosis, treatment, advice and referrals. Those services certainly fall within the commonly understood meaning of a “healing art.” We conclude that the statutory definition of “doctor or physician” in ORS 656.005(12) includes a nurse practitioner.5
We turn to the question whether a nurse practitioner may be designated as an “attending physician” as that term is defined in ORS 656.005(12). An attending physician is a doctor or physician who is “primarily responsible for the treatment of a worker’s compensable injury.” ORS 656.005(12). ORS 656.245(3) allows a worker to “choose an attending doctor or physician within the State of Oregon.” Those provisions appear to contemplate that a worker may select any doctor or physician in the state to be the attending physician. The legislature has not demonstrated any intent to impose higher professional standards on attending physicians than it imposes on doctors and physicians. Thus, to be eligible for designation [144]*144as an attending physician, a practitioner must be: (1) a “doctor or physician” under ORS 656.005(12); (2) capable of assuming primary responsibility for the treatment of the compensable condition; and (3) practicing in Oregon. We have already concluded that a nurse practitioner is included in the phrase, a “doctor or physician,” as that term is used broadly in ORS 656.005(12). Nurse practitioners are licensed to provide primary health care and are, by rule, “independently responsible” for health services. We therefore hold that those nurse practioners who practice in Oregon are eligible to be designated as attending physicians.6 To the extent that OAR 436-10-050 does not allow nurse practitioners to be designated as attending physicians, it is inconsistent with the legislative policy underlying ORS 656.005(12).
The decision of the Court of Appeals is reversed. The rule, OAR 436-10-050(4), is declared invalid to the extent set out in this opinion.
APPENDIX
The following is a breakdown of the way the term, “healing arts,” is used in other jurisdictions:
I. Statutes that exclude nursing from definitions of the term, “healing arts. ”
A. The following statutes define a “healing art” as one of several listed occupations which do not include nursing:
Connecticut: Conn Gen Stat Ann § 20-1 (West 1988) (“the practice of medicine, osteopathy, chiropractic, podiatry and naturopathy”).
Florida: Fla Stat Ann § 456.32(2) (1981) (for purposes of referring patients to hypnotists, healing arts practitioners are limited to practitioners of “medicine, surgery, psychiatry, dentistry, osteopathic medicine, chiropractic, naturopathy, podiatry, chiropody, and optometry”). See also Fla Stat Ann § 483.041(8) (West 1988) (dealing with health testing services) (“licensed practitioner of the healing arts” includes only a physician, a dentist, a podiatrist, or a naturopath).
[145]*145New Mexico: NM Stat Ann § 59A-22-32(B)(2) (1978) (for purposes of health insurance contracts, “practitioner of the healing arts” includes only chiropractors, dentists, medical doctors and surgeons, and osteopaths). See abo NM Stat Ann § 62-8-10 (applying the same definition to a statute prohibiting the termination of utility service to a residence in which a seriously ill person resides, if a practitioner of the healing arts certifies that termination of service might endanger that person’s life).
Kentucky: “Healing art” includes “the practices of medicine, osteopathy, dentistry, chiropody (podiatry), optometry, and chiropractic, but does not include the practices of Christian Science or midwifery.” Ky Rev Stat § 311.271(2) (a) (1983). The definition is not entirely clear, but it does not appear to include nursing.
B. The following statutes also exclude nursing from their definitions of the healing arts:
Dbtrict of Columbia: DC Code Ann § 2-1301 (2) (E) (1981) specifically excludes nursing from its definition of “the healing art.”
Texas: Tex Rev Civ Stat Ann art 4590e, § 2 (Vernon 1976) defines “healing art” as “any system, treatment, operation, diagnosis, prescription or practice for the ascertainment, cure, relief, palliation, adjustment or correction of any human disease, ailment, deformity, injury or unhealthy or abnormal physical or mental condition.” However, section 3 of that provision requires that all practitioners of “the healing art” use one of a list of legally required identifications. The listed identifications are appropriate only for practitioners of medicine, dentistry, chiropractic, optometry, chiropody and naturopathy. Nursing is not included.
II. Statutes with broad, general definitions.
These statutes generally define the term, “healing art,” as the diagnosis and treatment of human disease or disability. Theoretically, that definition is broad enough to encompass nursing, although it is not clear in any case whether it does so.
Kansas: Kan Stat Ann § 65-2802(a) (1985). Kansas does, however, have both a “Board of Healing Arts” and a “Board of Nursing.”
[146]*146Minnesota: Minn Stat Ann § 146.01 (West Supp 1988).
Nebraska: Neb Rev Stat § 71-101.01 (1986).
Nevada: Nev Rev Stat § 630.060(4) (b) (1983) (adds the requirement that “for the practice of which long periods of specialized education and training and a degree of specialized knowledge of an intellectual as well as physical nature are required”). See also Nev Rev Stat § 633.051 (same definition in chapter governing osteopathic medicine).
Oklahoma: Former Okla Stat Ann tit 59 § 702 (West 1971), repealed by Okla Laws 1973, c. 48.
Pennsylvania: 1 Pa Cons Stat Ann § 1991 (Purdon Supp 1988).
South Dakota: SD Codified Laws Ann § 36-2-1(3) (1986).
Tennessee: Tenn Code Ann § 63-1-102(2) (1986) (specifically includes practice of acupuncture).
Virginia: Va Code § 54-273 (Supp 1987).
DEFINITIONS FROM OTHER SOURCES
Ohio: An administrative rule governing habilitation centers for mentally retarded persons defines “practitioner of the healing arts” as “physicians, nurses, psychologists, occupational therapists, physical therapists, and speech pathologists/audiologists.” OAC 5123:2-15-01(B)(9) (Baldwin 1988).
Illinois: Lyon by Lyon v. Hasbro Industries, Inc., 156 111 App 3d 649, 509 NE2d 702 (1987), defined the term, “healing art,” for the purposes of the state “healing art malpractice” statute. The court concluded that the phrase “by definition implies an entire branch of learning dealing with the restoration of physical or mental health,” and that it was broad enough to cover ambulance service. Thus, an allegation that the service negligently failed to provide equipment necessary to facilitate emergency health care was an allegation of “healing art malpractice.” 509 NE2d at 706.