OPINION
This appeal concerns the valuation for ad valorem tax purposes of a portion of the potash products of IMC (International Minerals & Chemical Corporation). ’ The dispute as to the valuation arose because of a formula used in arriving at the valuation. The specific issues are: (1) was the production involved subject to valuation for tax purposes under § 72-6-7.1, N.M. S.A. 1953 (Repl.Vol. 10, pt. 2, Supp.1971); (2) was the formula a method in general use under § 72-25-5, N.M.S.A.1953 (Repl. Vol. 10, pt. 2, Supp.1971); (3) was the formula a regulation under § 72-25-6, N.M. S.A.1953 (Repl.Vol. 10, pt. 2, Supp.1971); (4) was use of the formula prohibited be*404cause its use was a change in existing procedure; and (5) was the formula arbitrary ?
The potash products involved are sylvanite, also known as muriate, and langbeinite, also known as sulphate of potash magnesium. The processing of these items includes a sorting by size or grades. One of the results of this sorting is material called “fines.” The “fines” differ in two ways from the products that IMC sells on the market. They are a smaller particle size and they have a slightly lower potassium oxide content. IMC uses the “fines” as feed material in its postassium sulphate plant.
Section 72-6-7.1, supra, required the state tax commission to value potash mineral property. However, § 72-25-3, N.M.S.A. 1953 (Repl.Vol. 10, pt. 2, Supp.1971) transferred this duty to the property, appraisal department. IMC protested the department’s assessed value of the “fines.” The property appeal board, after a hearing, denied the protest. IMC appeals the decision of the property appeal board. See §§ 72-25-10, 72-25-18 and 72-25-19, N.M. S.A.1953 (Repl.Vol. 10, pt. 2, Supp.1971).
Was the production involved subject to valuation for tax purposes?
Section 72-6-7.1(B), supra, provides that production from potash mineral property is to be valued “. . . at fifty per cent [S0%] of marlcet value of the output of the property for the prior year. . . .” The tax year involved is 1970. The output involved is the “fines” for 1969. The issue under this point concerns “market value” for tax purposes.
It is undisputed that the “fines” have no commercial market; further processing is required. That processing occurs in IMC’s potassium sulphate plant. The valuation point involved here occurs prior to the processing; it occurs while the material exists as “fines.” Since there is no commercial market at this point, IMC infers that the fines may not be taxable because the valuation for tax purposes under § 72-6-7.1, supra, is based on “market value.”
We treat the portion of IMC which produces the “fines” as the seller and IMC’s potassium sulphate plant as the buyer. As between this fictional seller and buyer there is an exchange value. The exchange value is the “market value” in this situation. Kaiser Steel Corporation v. Property Appraisal Department, (Ct.App.), 490 P.2d 968, decided September 3, 1971. The “fines” were to be valued for tax purposes under § 72-6-7.1, supra.
Was the formula a method in general use?
Section 72-25-5, supra, provides in part: “When not otherwise determined by law, and without regard to ownership, the taxable value of property shall be determined by methods in general use. . . .” The starting point for determining taxable value is market value. See §§ 72-6-7.1, supra, and 72-25-2, N.M.S.A.1953 (Repl.Vol. 10, pt. 2, Supp.1971). The property appraisal department determined the market value of the “fines” for tax purposes by using a formula. IMC claims the formula was not a method in general use.
The details of the formula are not involved in this point; the issue is whether the formula was a method of valuation in general use. Findings of the property appeal board, supported by substantial evidence, are: Both IMC and Duval Corporation, another potash company, protested their assessments for the 1969 tax year. An agreement as to the assessments was reached with both companies. Iia the agreed assessments, the property appraisal department valued the “fines" by using the formula now disputed. For the 1970 tax year, Duval Corporation valued its “fines” by voluntarily using the formula in question. Duval Corporation also used this valuation as a “representative market price” of the “fines” in calculating its depletion allowance on its 1969 federal income tax.
In addition to these findings, the Duval Corporation witness testified that its valuation pursuant to the formula was the “representative market price theory;” that use of this theory was acceptable prac*405tice; that there are other acceptable practices ; that these different acceptable practices are those allowed under the Internal Revenue Code in connection with depletion allowances. We do not consider the “acceptable practices” under the federal Internal Revenue Code as a valuation method determined by New Mexico law to be used for our State tax. These acceptable practices under federal law are, however, evidence of a method in general use.
The foregoing evidence supports the conclusion of the property appeal board that the formula used in determining market value of the “fines” was a method in general use in determining taxable value.
Was the formula a regulation?
Section 72-25-6(A), supra, provides in part: “Unless a specific method for appraising property is provided by law, the department shall adopt regulations for appraising each kind of property in the state. ...” Section 72-25-8, N.M.S.A.1953 (Repl.Vol. 10, pt. 2, Supp.1971) sets forth a procedure for'adopting regulations. It is undisputed that the property appraisal department did not follow the procedure of § 72-25-8, supra, before utilizing the questioned formula.
The issue is whether the' formula is to he classified as a regulation. IMC contends the formula amounts to a regulation because it is a device for appraising its property; that is, a method used in determining the taxable value of its property. See § 72-25-2, supra.
The property appraisal department makes two'responses. First, it asserts that no regulation is required if a specific method for appraising property is provided by law. The department asserts § 72-6-7.1, supra, provides a-specific method. We do not consider this response because it does not appear that this theory was presented tó the property appeal board. It may not change its theory of the case on appeal. Board of Education v. State Board of Education, 79 N.M. 332, 443 P.2d 502 (Ct.App.1968). Second, it contends that “fines” do not amount to a “kind of property” within the meaning of § 72-25-6(A), supra.
We agree with IMC to this extent —the formula is a method used in appraising the “fines.” It does not follow, however, that a “regulation,” adopted pursuant to statutory procedure, was required before the formula could be used. Regulations are required for appraising “each kind of property.” “Kind” is not defined in the statute. Accordingly, it is to be given its ordinary meaning. Albuquerque Nat. Bank v. Commissioner of Revenue, 82 N.M. 232, 478 P.2d 560 (Ct.App.1970).
One of the definitions of “kind” as a noun in Webster’s New Third International Dictionary (1966) is “category” or “class.” Black’s Law Dictionary (1951) indicates “kind” means a “generic class” and defines “in kind” as “in the same kind, class, or genus.” We hold “kind of property” in § 72-25-6(A), supra, means general categories or generic classes of property. Compare Alabama By-Products Corporation v. Patterson, 258 F.2d 892 (5th Cir. 1958), cert. denied, 358 U.S. 930, 79 S.Ct. 318, 3 L.Ed.2d 303 (1959); Fleming v. Commissioner of Internal Revenue, 241 F.2d 78 (5th Cir. 1957), rev’d, Commissioner of Internal Revenue v. P. G. Lake, Inc., 356 U.S. 260, 78 S.Ct. 691, 2 L.Ed.2d 743 (1958). The property appraisal department is not required, under § 72-25-6 (A), supra, to adopt regulations for specific or individual types of property within general categories or generic classes of property.
In this case we are not concerned with regulations for appraising the general category of potash mineral property. See § 72-6-7.1(B), supra. The issue involves a particular type of potash mineral property; specifically, “fines.” We hold that the property appraisal department’s use of the formula in determining the market value of the “fines” was not a regulation within the meaning of § 72-25-6(A), supra.
*406 'Was use of the formula prohibited because its use was a change in existing procedure?
Section 72-25-6(H), supra, states: “All existing orders, rulings, regulations which have been' filed 'with' the state records center, and existing procedures of the state tax commission shall be continued in full force and effect until revoked, superseded or amended by the department; Provided however, that no public hearing shall be required on the repeal of regulations in effect prior to the "date of this act.”
The issue under this point concerns “existing procedures of the' state tax commission.” The' authority, powers and duties of the state tax' 'commission were transferred to the property appraisal department effective'February 26, 1970. See '§ 72-25-3, supra, ánd Laws 1970, ch. 31, § 23. IMC contends that the existing procedure of the state tax commission on that date was to value the “fines” at $17.65 per K20 ton. IMC asserts this valuation must be used and not the valuation derived from the formula.'
The evidence is to the effect that the $17.65 per K20 ton valuation for the “fines” is an arbitrary figure. Even though arbitrary, nevertheless it was the valuation used by the state tax commission through the. 1968 tax year. In addition, there is evidence that the state tax commission was using the $17.65 per K2O ton valuation in connection with the 1969 tax year. We will assume that .this valuation was an existing procedure of the state tax commission. At the time the property appraisal department succeeded the state tax commission (February 26, 1970), the valuation for the 1969 tax year was under protest. The compromise settlement for the 1969 taxes was reached later in 1970. This settlement did not use the $17.65 per K20 ton valuation; rather, the “fines” were valued according to the formula. The dates involved show the formula was employed by the property appraisal department and not by the state tax commission.
Thus, under the assumption that the $17.65 per IC20 ton valuation was an existing procedure, this valuation was the existing procedure under the state tax commission. The change to the formula occurred under the property appraisal department.
IMC seems to assert that the valuation procedure in existence on February 26, 1970 must be applied. The inference is that no change may be made in an existing procedure. Section 72-25-6(H), supra, is to the contrary. Existing procedures were continued but only until revoked, superseded or amended.
IMC also seems to contend that the $17.65 per K20 ton procedure had not been revoked, superseded or amended. The property appeal board found, however, that the valuing procedure by the-property appraisal department for the “fines” in the 1969 tax year was through use of the formula. This formula having superseded the $17.65 per K20 ton valuation procedure for the 1969 tax year, the $17.65 per K20 ton valuation was not an existing procedure for the 1970 tax year.
Although the property appraisal department used the formula in valuing the “fines” in the compromise settlement for the 1969 tax year, IMC asserts it did not agree to the formula. It contends it only agreed to the overall settlement 'figure and argues that “ . . .it would not be proper to hold that Appellant [IMC] had in fact agreed to the assessment of the feed material [the fines] on the basis of the formula used. . . . ” This argument mistakes the finding of the property appeal board. It did not find that IMC agreed to use of the formula. It found that IMC agreed to an assessment in which the property appraisal department used the formula in valuing the “fines.” The significance of this finding is that the $17.65 per K20 ton valuation was not used in the 1969 tax settlement. It had been superseded.
*407We hold therefore that § 72-25-6(H), •supra, did not require the property appraisal department to use the $17.65 per K2O ton valuation for the 1970 tax year.
Was the formula arbitrary?
One of the statutory grounds for setting aside the decision of the property appeal board is that the decision is arbitrary. Section 72-25-19 (H) (6), supra. IMC contends the decision is arbitrary because the formula was used in determining the market value of the “fines.” IMC’s position is based on the fact that the sylvanite and langbeinite are graded by particle size. There are “coarse” particles .and “standard” particles, and the resultant “fines.” There is a difference in the market price for “coarse” and “standard” and no commercial market for the “fines.” IMC asserts the formula does not consider the difference in price based on par•ticle size and for this reason is arbitrary.
The formula used “ . . . the average value per ton of the potash products sold in the market as either coarse or standard sized sylvanite and langbeinite, adjusted downward to account for the slightly lesser potassium oxide content. ...” The result was considered to be the market value of the “fines,” and was so found by the property appeal board. The issue here is not the adjustment for the lesser potassium oxide content. The issue is “average value” used in the formula when that average is based on “coarse” and '“standard” sizes of the ore.
If something is “arbitrary” it is “not . . . according to reason or judgment.” Webster’s Third New International Dictionary, supra, Black’s Law Dictionary, supra. Duval Corporation voluntarily used the formula in valuing the “fines” for its 1970 taxes. There is evidence that the “fines” are “ . . . more closely associated with the standard grade than with the other two grades.” The two grades, or particle sizes, other than “standard” and “fines” are “coarse” and “granular.” There is evidence that “ . . . the figures you used for the products sold on the market, the figures 'o’f the- K20 content does indicate . . - 7 .-that 'you adjusted it for. grade, differential by taking an average;., ..... . ” We need go no further than this evidence that the average value of market sales indicates an adjustment for the differences in grades or sizes. With this evidence we cannot say, as a matter of law, that the formula was arbitrary.
The order of .the property appeal board denying IMC’s protest is affirmed.
It is so ordered.
HENDLEY, J., concurs.