O'CONNELL, J.

This is a suit for declaratory relief under ORS 28.130, the Uniform Declaratory Judgments Act. Plaintiffs attack an assessment subjecting their interests in certain grazing lands in Grant county to an ad valorem tax imposed upon them under ORS 307.060. Defendants, the Grant county assessor and sheriff and the State Tax Commission, appeal from a judgment for plaintiffs.

The interests subject to be taxed are grazing privileges on lands owned by the federal government. These interests were created pursuant to Section 15 of the Taylor Grazing Act ( 43 USCA 315m) which authorizes the Secretary of the Interior to lease certain lands in the public domain for grazing purposes.

ORS 307.060, under which the tax was imposed, reads as follows:

" 307.060 Property of the United States held by a person under lease or other interest less than fee. Real and personal property of the United States or any department or agency thereof held by any person under a lease or other interest or estate less than a fee simple, other than under a contract of sale, shall be assessed and taxed as for the full true cash value thereof subject only to deduction for restricted use. The lien for the tax shall attach to and be enforced against only the leasehold, interest or estate in such real or personal property. This section shall not apply to real or personal property held by this state or any county, municipal corporation or political subdivision therein which is:

"(1) In immediate use and occupation by such political body; or

"(2) Required, by the terms of the lease or agreement, to be maintained and made available to the Federal Government, as a military installation and facility."

Plaintiffs contend that the grazing privilege granted to them by the Secretary of the Interior is not "a lease or other interest or estate less than a fee simple" described in ORS 307.060. They further contend that if their interests are subject to taxation under ORS 307.060 the statute is unconstitutional because it purports to levy a tax on the property of the United States, and because it discriminates against lessees of the United States.

The trial court held that ORS 307.060 is constitutional but that plaintiffs' interest "constitutes not a leasehold interest but merely a license to use the property for grazing."

Defendants appeal from that part of the judgment which declares that plaintiffs have no taxable interest; plaintiffs cross-appeal from that part of the judgment which declares that ORS 307.060 is constitutional.

The Taylor Grazing Act makes provision for the granting of two different types of grazing privilege, depending upon whether the land is within or outside an established grazing district. Where the land is within a grazing district the Secretary of the Interior is authorized by Section 3 of the Act ( 43 USCA § 315b) to issue a grazing permit; where the land is not included in a grazing district the Secretary is authorized by Section 15 ( 43 USCA § 315m) to lease it upon such terms as he may prescribe. The pertinent parts of Sections 3 and 15 of the Taylor Grazing Act read as follows:

"Sec. 3 The Secretary of the Interior is authorized to issue or cause to be issued permits to graze livestock on such grazing districts to such bona fide settlers, residents, and other stock owners as under his rules and regulations are entitled to participate in the use of the range, upon the payment annually of reasonable fees in each case to be fixed or determined from time to time, and in fixing the amount of such fees the Secretary of the Interior shall take into account the extent to which such districts yield public benefits over and above those accruing to the users of the forage resources for livestock purposes. Such fees shall consist of a grazing fee for the use of the range, and a range-improvement fee which, when appropriated by the Congress, shall be available until expended solely for the construction, purchase, or maintenance of range improvements. * * * Such permits shall be for a period of not more than ten years, subject to the preference right of the permittees to renewal in the discretion of the Secretary of the Interior, who shall specify from time to time numbers of stock and seasons of use. * * * So far as consistent with the purposes and provisions of this Act, grazing privileges recognized and acknowledged shall be adequately safeguarded, but the creation of a grazing district or the issuance of a permit pursuant to the provisions of this Act shall not create any right, title, interest or estate in or to the lands. ( 43 U.S.C. § 315b)

"* * * * *

"Sec. 15 The Secretary of the Interior is further authorized, in his discretion, where vacant, unappropriated, and unreserved lands of the public domain are so situated as not to justify their inclusion in any grazing district to be established pursuant to this Act, to lease any such lands for grazing purposes, upon such terms and conditions as the Secretary may prescribe * * *. ( 43 U.S.C. § 315m)"

The intention of Congress to provide for the creation of two distinct types of interest, i.e., the "permit" under § 315b and the "lease" under § 315m is apparent from an examination of other sections of the Taylor Grazing Act. The section which most clearly evidences this intent is § 315p. This section implements § 315g which authorizes the Secretary of the Interior to exchange grazing land for state land. § 315p provides as follows:

"§ 315p. Exchange of lands; issuance of patent subject to outstanding lease.

"The Secretary of the Interior in adjudicating State exchanges, under section 315g of this title, involving lands embraced in outstanding leases under section 315m of this title issued prior to the filing of the State exchange application, is authorized upon the request of any State to issue patent to the State, subject to such outstanding lease: Provided, That the United States shall not by reason of the issuance of any such patents be required to account to the State for any money due and collected prior thereto as rent for any part of the then-current annual rental period except as was, on August 24, 1937, provided by law. (Aug. 24, 1937, ch. 744, 50 Stat. 748.)" [Emphasis added]

The use of the terms "outstanding lease," "rent" and "rental period" are, of course, indicative of an intention to regard the interests created under § 315m as leases. But what is more important, § 315p recognizes that § 315m leases create substantial interests in land and that the patent issued by the Secretary of the Interior is taken subject to that interest. The interest acquired under a § 315b permit is not excepted under § 315p because the grazing privilege acquired under a permit is not an interest in land. Section 315b specifically provides that permits "shall not create any right, title, interest, or estate in or to the lands."

The difference between a permit and a lease is also recognized in § 315i which provides for a different disposition of the moneys collected under § 315b and under § 315m.

The distinction between the "permit" to graze authorized under Section 3 and the "lease" of grazing lands under Section 15 is reflected in the forms prepared by the Department of Interior for use in memorializing the grant of the privilege in each instance. The grant of a privilege to graze under Section 3 is made by two instruments which are entitled "____ Year Grazing Permit" and "Application For Grazing License or Permit." The latter, when endorsed, operates as the permit itself. The permit is granted for the grazing of a certain number of cattle during a designated period described in the permit as a certain number of animal-unit months. The permit does not describe a specific area of land upon which the permittee is entitled to run his cattle other than the designation of the grazing district to which he is limited. The privilege granted under a Section 3 permit is not exclusive; permits may be granted to more than one person for a single grazing district.

The form of instrument used to grant the right to graze under Section 15 is quite different. It is entitled "Application To Lease and Lease of Lands for Grazing Livestock." This application, when accepted by the federal agency, constitutes the lease itself. Unlike the grazing permit granted under Section 3, the lease contains a legal description of the land to which the grazing right extends in terms of range, township, section and government lots. The lessee has the exclusive right to use the described land for grazing as against all other persons. Throughout the instrument the language commonly found in leases is used. In the application portion of the instrument the applicant "applies to lease all or any part of the lands described," and he agrees that his signature to the application shall also constitute an "acceptance of this lease when executed by the proper officer in behalf of the United States." At the foot of the application form a provision for acceptance is in the following language: "A lease for the lands described * * * is hereby issued subject to payments of rental due and to the provisions herein, for a period of ____ years." The instrument contains various specific provisions defining the rights and duties of the "lessee," all of which are cast in the language of a lease. The "lessee" agrees to pay the required "rental"; if it is not paid within the time specified "the lease shall become null and void." Provision is made for a readjustment of the "rental" at the end of each three-year period. "Subleases" are not authorized and the lessee may not "assign this lease or any interest herein without the prior written consent of the signing officer." The default clause is similar in form to that found in leases: "If the lessee shall default in the performance or observance of any of the terms, covenants, and stipulations hereof, or of the regulations now or hereafter in force and such default shall continue 30 days after service or written notice thereof by the lessor, then the signing officer may terminate and cancel this lease." Likewise with respect to the clause indicating the intention that the promises run with the land: "It is further covenanted and agreed that each obligation hereunder shall extend to and be binding upon, and every benefit shall extend to and inure to the heirs, executors, administrators, successors and assigns of the respective parties hereto." There is other language in the form which indicates that the creation of a leasehold interest was intended.

It appears, therefore, that not only does the Taylor Grazing Act itself indicate that Congress intended to provide for two distinct types of grazing privileges — a license under Section 3 and a lease under Section 15 — but also that the instruments used by the Department of the Interior in granting grazing privileges under the two sections are designed to carry out the legislative distinction.

Admittedly the name which the parties attach to a relationship does not ipso facto determine the nature of the legal relationship created; the essential elements of the relationship in question must be present. The mere fact that the parties describe an instrument as a lease does not conclusively establish the existence of a leasehold interest. Baseball Publishing Co. v. Bruton, 302 Mass. 54, 18 N.E.2d 362, 119 ALR 1518 (1938); Lewis v. Baxter Laundries, 254 Mich. 216, 236 N.W. 239 (1931); Whiteside v. Oasis Club, 162 Mo App 502, 142 S.W. 752 (1912). But the language employed by the parties may be an aid to construction if the instrument is ambiguous. Alfano v. Donnelly, 285 Mass. 554, 189 N.E. 610 (1934). In determining the intention of the parties, "[t]he courts construe the whole mass of words and not merely some of them." Strandholm v. Barbey, 145 Or. 427, 441, 26 P.2d 46 (1934).

In the case at bar plaintiffs contend that no interest in land was created by the grant of the grazing privilege to them and that plaintiffs are "licensees" only. The defendants argue that a leasehold interest was granted to each of the plaintiffs. Thus we are called upon to determine whether a lease or a license was created.

To create a leasehold interest the lessee must be granted the right of possession. A license is a revocable privilege to use land in the possession of another. Restatement of Property, Servitudes, § 514. It is commonly said that the lessee must have "exclusive possession," Chain Belt Co. v. United States, 115 F. Supp. 701, 708 (Ct.Cl. 1953); White v. Maynard, 111 Mass. 250, 255, 15 Am Rep 28 (1872); Mallam v. Trans-Texas Airways, 227 S.W.2d 344, 346 (Tex Civ App 1949); Conaway v. Time Oil Co., 34 Wn.2d 884, 210 P.2d 1012, 1017 (1949), but this is not strictly true because all possessory interests, including even a fee simple, are subject to limitations making the possessory right something less than exclusive. Translating "exclusive possession" to mean the right to exclude others, it is apparent that as against the lessor the exclusiveness of possession may vary depending upon the restrictions imposed upon the transferee's use by the creating instrument. Seabloom v. Krier, 219 Minn. 362, 18 N.W.2d 88, 91 (1945); Peterson v. Vak, 160 Neb. 450, 70 N.W.2d 436, 439, 51 ALR2d 1221 (1955), amended 160 Neb. 708, 71 N.W.2d 186 (1955); 1 Tiffany, Real Property (3rd Ed) § 79. Even in the absence of express reservations in the creating instrument, the lessee's right to exclude others is less than complete for the landlord always has the right to enter to demand rent and to make repairs. 1 Tiffany, Real Property (3rd Ed) § 79. As we shall illustrate more specifically later, it is common in the creation of a leasehold interest to limit the lessee's use of the property to certain specified activities. In the sense that he does not have the privilege to use the property for proscribed activities, the lessee's possession is not exclusive. Further, even though the lessee's right to use the premises is not so restricted, his entire estate may be limited by the creating instrument so as to be subject to termination upon the occurrence of some stated event; and the stated event may involve no element other than an exercise of the grantor's volition. Restatement, Property, § 45, comment g. In such case the lessee's possession is exclusive, as to the lessor, only in a limited sense.

Where the right reserved in the transferor to terminate the transferee's interest is extensive, the line between a lease and a license becomes indistinct and the judicial effort to state the difference is often less than convincing. Contributing to the difficulty in classifying possessory and non-possessory interests in the occupation of land is the fact that possession does not have a fixed meaning. "Possession * * * is a variable term which may mean different things for different purposes." 1 American Law of Property, § 3.3, p 180.

A part of the variability in the meaning of possession arises out of the fact that possession has meaning only in terms of actual or potential use and because the uses to which land may be put vary from parcel to parcel. When the property is amenable to many uses, the right to use it for a single limited purpose might not constitute possession; yet, the same right to use may well be regarded as possessory if the land in question is susceptible to only a limited number of uses. And so, in the present case, since the land in question is of little use for anything other than grazing, mining and recreation, the grant of the right to use it for grazing purposes embraces a substantial part of all of the practical uses to which the land may be put. Therefore, although such use is limited, it is relatively "exclusive."

In another context we have noted that the acts necessary to constitute possession must be related to the character of the land involved. In Springer v. Durette, 217 Or. 196, 200-201, 342 P.2d 132 (1959), a case involving claim to title by adverse possession, we recognized that the grazing of livestock upon wild land was sufficient to constitute possession. There we said that "[t]he claimant need only show that he `has acted toward the land in question as would an average owner, taking properly into account the geo-physical nature of this land,' 6 Powell on Real Property, § 1018, p 731, considering the `reasonable uses for which the land in question was suitable.' 6 Powell at p. 717." Similarly, in the case at bar, the character of the land in question must be considered in determining whether the plaintiffs' right to graze cattle constitutes a possessory interest.

We have examined separately each of the limitations on the lessees' use of the premises. It is possible, of course, that although a single restriction or limitation on use separately considered may not negative the lessee's so-called exclusive possession, the aggregate of two or more such restrictions and limitations may well do so. In the present case the restrictions and limitations taken together do not, in our opinion, reduce plaintiffs' interest to one which is merely non-possessory in character. There is no exact judicial gauge which can be set against the facts to prove our conclusion with mathematical precision. The exclusiveness of one's occupancy is a matter of degree. We can only compare the respective ownership interests — principally the usufructuary rights — of the transferor and the transferee, and if we find that the transferee has been granted the privilege of occupancy together with a sufficient share of these interests we describe his right as "possession."

The revocability of the occupant's interest is not a controlling factor in classifying it as a possessory or non-possessory interest. From the standpoint of the prospect of its termination the lessee's interest may, by the reservation in the lessor of a right of entry or right of revocation, be as precarious as the interest of a mere licensee. But this certainly does not preclude the transferee from taking possession, for a tenancy at will is a common and traditional estate in land. It is, then, the character of the occupant's right to use until his interest is terminated which is regarded as the significant factor. If, prior to termination, the transferor can rightfully interfere with every use the occupant might make of the premises, the interest is clearly a mere license. If any interference by the transferor is prohibited, the transferee's interest is clearly a leasehold. When a case does not present either of these extremes we are required to determine whether the right to use bargained for by the transferee is substantial enough to warrant giving him the benefits (or imposing upon him the burdens) which legal tradition has attached to possessory interests. Generally the substantiality of the occupant's interest is tested by the inquiry: Does he have sufficient control over the premises to warrant the label of possession? For the most part, this inquiry is judicially answered by matching the facts in the case before the court with other cases where a similar situation has been the subject of adjudication. Undoubtedly the policy which will be served by classifying the interest in a particular way is frequently at the core of this matching process. Indeed, it has been suggested that the judicial process here is the reverse of that which we have assumed, and that a declaration of the occupant's rights or duties do not follow from the classification of his interest as possessory, but rather, that his interest is classified as possessory or non-possessory because it is decided for reasons of policy that he should or should not have certain rights or duties. In re Owl Drug Co., 12 F. Supp. 439, 442 (D.C. Nev. 1935). See also, McDougal and Haber, Property, Wealth, Land (1948) pp 118, 342. Cf., Shartel, Meanings of Possession, 16 Minn L Rev 611 (1932).

Testing plaintiffs' interests upon the basis of the criterion of control, we are of the opinion that the "lease" created in them possessory interests. The creating instrument clearly reveals the intent to invest plaintiffs with the right to exclude others, including the grantor, except in the special circumstances recited. The reservation by the grantor of the right to reduce the grazing area or to permit other specified uses and the recognition of the privilege in others to use the premises for limited purposes do not, in our opinion, reduce plaintiffs' privilege to a mere non-possessory interest. In all other respects plaintiffs' rights were "exclusive." "Restrictions in the rights of tenancy which do not affect its fundamentals should not be interpreted as destroying the relationship." In re Owl Drug Co., 12 F. Supp. 439, 445 (D.C. Nev 1935). Moreover, the duties imposed upon the "lessees" by the terms of the creating instrument are those normally devolving upon the possessor of land. Thus in the use of the land plaintiffs were required to take reasonable precaution to prevent grass, brush and forest fires and to suppress them if they started. Likewise, they were obligated to comply with the laws with respect to the cost and maintenance of fences. And, they covenanted to maintain in good repair any range improvements on the leased premises.

Because of the concern for the public interest which government agencies have in the management of lands entrusted to their supervision, the leases which they execute cannot be expected to follow exactly the pattern of traditional commercial leases. Leasing arrangements such as the one before us are sui generis and the interest created in the transferee should not be declared to be non-possessory simply because it does not conform exactly to the interest created in lessees under the usual form of lease. Cf., Comment, Agreements for Leasing Departments in Retail Stores, 35 Mich L Rev 95, 101 (1936), where it is contended that such leasing agreements should be treated as sui generis to "enable them to serve adequately the modern business needs they are aimed to meet."

The exclusiveness of plaintiffs' possession is negatived to some extent by various provisions in the instrument permitting the lessor and third persons to use the premises under certain circumstances. The lessees agree "to allow authorized representatives of the Department of the Interior at any time to enter the leased lands for the purpose of inspection, and allow federal agents, as well as game wardens, at all times to enter the leased lands on official business." The reservation in the lessor of the right to enter leased premises for inspection purposes is commonly provided for in the execution of leases. Lieberman, Effective Drafting of Leases for Real Property (1956) IX-12, pp 166-168. The privilege of entry reserved to game wardens and federal agents is not to be interpreted as permitting entry which would materially interfere with the lessees' right of grazing and is, therefore, consistent with plaintiffs' substantially exclusive possession. The same may be said with respect to the provision permitting entry by "miners, prospectors for minerals, and other persons entitled to enter such area for lawful purposes" and permitting entry for hunting and fishing purposes.

The lessor reserves the right "to permit under applicable laws and regulations, the use and disposal of the mineral, timber, or other resources on or in the leased lands." It is very common in the grant of estates in both government and privately owned land to reserve mineral, timber and other natural resources. Lieberman, op. cit. supra, IV-17, pp 45-46, VI-7, pp 78-79. Therefore, we do not attach any persuasive significance to these reservations.

By the terms of the lease, the lessor reserves the right to "classify and dispose of, under applicable laws and regulations, pursuant to [public land laws] any part or all of the leased lands," provision being made for compensation of the lessee if such disposition is made. The lessor also reserves the right to reduce the leased area if it is "unreasonably excessive for the number of stock owned by the lessee, or if it is determined that such area is required for the protection of sources of water supply to communities, or for camping places, stock driveways, roads and trails, or town sites, or for feeding grounds near communities for the use of domestic livestock or near the slaughtering or shipping points for use of stock to be marketed or for other public purposes." In essence, these reservations create in the transferee an interest which is, on the occurrence of a condition subsequent, subject to a power of termination reserved in the grantor. Many illustrations may be given of leases in which the lessor has the power to terminate the lessee's interest upon the occurrence of a stated event. The stated event may be, for example, the lessor's election to dispose of the land by sale, Gostin v. Needle, 185 Md. 634, 45 A.2d 772, 163 ALR 1013 (1946), or the insolvency, bankruptcy or receivership of the lessee, Smith v. Hoboken P.W. S.S. Connecting Co., 328 U.S. 123, 66 S Ct 947, 90 L Ed 1125, 168 ALR 497 (1946). The reservation of such a power is not uncommon in government grants of estates. See, 43 USCA §§ 641-648; 43 USCA § 869; 16 USCA § 32. The reservation of the power to terminate the lessee's interest as to a part only of the land is likewise consistent with the grant of a possessory estate.

Of greater importance in classifying the occupant's interest is the control reserved by the transferor over the use of the premises, as distinguished from the reservation of a right to terminate the estate created. Here again the cases are bountiful recognizing a lease even though lessee's use is in some respects subject to lessor's control. The proposition is illustrated by the cases in which a part of the area in a store is "leased" to a concessionaire to be operated as a particular department. Although there is some conflict of authority, there are numerous cases holding that the concessionaire's interest is a leasehold. This result has been reached even though the lessor reserves the right to designate the space to be occupied at any time, Beckett v. City of Paris Dry Goods Co., 14 Cal.2d 633, 96 P.2d 122, 123 (1939); or to relocate the department, In re Owl Drug Co., 12 F. Supp. 439 (D.C. Nev 1935); or to discharge lessee's employees, Beckett v. City of Paris Dry Goods Co., supra, 96 P.2d at 123; see also, Stratis v. McLellan Stores Co., 311 Mass. 525, 532, 42 N.E.2d 282, 142 ALR 1393 (1942); or supervise lessee's employees, In re Owl Drug Co., supra, 12 F Supp at 444; or dictate lessee's credit policy, In re Owl Drug Co., supra, 12 F Supp at 444; or requires that lessee turn over all receipts to the lessor's cashier, Beckett v. City of Paris Dry Goods Co., supra, 96 P.2d at 123; see also Stratis v. McLellan Stores Co., supra, 311 Mass. at 531-532; or that all business be conducted in the name of the lessor, In re Owl Drug Co., supra, 12 F Supp at 444; or generally that the business is to conform to the standards of the lessor, Meers v. Munsch Protzmann Co., Inc., 217 App. Div. 541, 217 NYS 256, 258 (1926).

Other adjudicated cases have recognized the creation of a lease where lessor has reserved a part of the use of the premises. Harrelson v. Miller Lux, 182 Cal. 408, 188 P. 800 (1920) (lessor reserved use of a certain room in the leased dwelling and right to pasture four animals on the premises); Polner v. Arling Realty, 194 Misc. 598, 86 NYS2d 891 (1949) (space in apartment building leased to installer of laundry equipment); McKennon v. Anderson, 49 Wn.2d 55, 298 P.2d 492 (1956) (lease of major portion of barn and surrounding yard).

There is ample authority for the proposition that a leasehold or other corporeal interest may be created even though the transferee has the right to use the premises only for a specified limited purpose. Leases commonly contain covenants limiting the use of the demised premises to specified purposes. In re Owl Drug Co., supra (space in department store leased for toilet goods department); Commercial Auto Loan Corp. v. Keith, 79 Ga. App. 268, 269, 53 S.E.2d 381 (1949) (use restricted to "loans and automobile financing"); Asa G. Candler, Inc. v. Georgia Theatre Co., 148 Ga. 188, 189, 96 S.E. 226, LRA1918F 389 (1918) (to be operated "as a first-class theater catering to the best class of people"); Heywood v. Fulmer, 158 Ind 658, 32 N.E. 574, 18 LRA 491 (1902); ("exclusive right to all sand and gravel" for specified time "excluding all other parties from said premises held to be a lease); Denecke v. Miller and Son, 142 Iowa 486, 119 N.W. 380 (1909) (right to store electrical supplies in storeroom used by lessor for purposes of his own); Tynes v. Kelly, 116 So.2d 54, 55 (La App 1959) ("`to be leased as a "drug store" only'"); Grossenbacher v. Daly, 287 S.W. 781, 782 (Mo App 1926) ("`to be used as a shoe retail store only, with the privilege of living in the rear'"); Burns Schaffer Amusement Co. v. Conover, 111 N.J.L. 257, 168 A. 304 (1933) (for moving picture or theater business only); Colonial Operating Corp. v. Hannon Sales Serv., Inc., 178 Misc. 879, 34 NYS2d 116, 117 (1942), reversed 178 Misc. 885, 36 NYS2d 745 (1942), modified 265 App. Div. 411, 39 NYS2d 217 (1943) (to be used "only for a showroom for automobiles and automobile accessories"); Lamken v. Miller, 181 Wn. 544, 44 P.2d 190 (1935) (grant of concession to sell food at race track); Greene Line Terminal Co. v. Martin, 122 W. Va. 483, 10 S.E.2d 901 (1940) (lease of public wharf).

In many cases where the privilege of use is limited to the severance of a part of the land itself the grantee's interest is described as a lease. Lehigh Zinc Iron Co. v. Bamford, 150 U.S. 665, 14 S Ct 219, 37 LEd 1215 (1893); Nelson v. Republic Iron Steel Co., 240 F 285 (8th Cir 1917); Berwind-White Coal Min. Co. v. Martin, 124 F 313 (3rd Cir 1903); Lewes Sand Co. v. Graves, 40 Del (1 Terry) 189, 8 A.2d 21 (1939); Heywood v. Fulmer, supra; Knight v. The Indiana, Etc., Co. et al., 47 Ind 105, 17 Am Rep 692 (1874); State v. Royal Mineral Ass'n., 132 Minn. 232, 156 N.W. 128 (1916); In re Owsley's Estate, 122 Minn. 190, 142 N.W. 129 (1913); State v. Evans, 99 Minn. 220, 108 N.W. 958, 9 Ann Cas 529 (1906); Woodruff v. Gunton, 222 Pa. 384, 71 A. 851 (1909); Gilmore v. The Ontario Iron Company, 86 N.Y. 455 (1881). As said in Heywood v. Fulmer, supra, 158 Ind at 660, "A lease may not only confer upon the lessee the right to the occupancy of the leased premises, either generally for the time limited, or for some specific purpose, or in some specific manner, or the right to occupy and cultivate and to remove the products of cultivation, but it may confer upon him the power to occupy and remove a portion of that which constitutes the land itself." Where the grant consists only of the privilege of severing and removing a part of the land itself, the grantor retaining possession, the interest transferred is more properly regarded as a profit a prendre. See, Bingham v. Salene, 15 Or. 208, 212-213, 14 P. 523, 3 Am St Rep 152 (1887); Hahner, An Analysis of Profits a Prendre, 25 Or L Rev 217 (1946). Cf., Saratoga State Waters Corporation v. Pratt, 227 N.Y. 429, 125 N.E. 834, 839 (1920). The grant of the privilege to pasture livestock on land which is possessed by the grantor is a profit a prendre. Baker v. Kenney, 145 Iowa 638, 124 N.W. 901, 903 (1910); Deseret Livestock Co. v. Sharp, 123 Utah 353, 259 P.2d 607, 610 (1953); 1 Thompson, Real Property (Perm ed) § 270. In the case at bar the language of the "lease" reveals an intent to transfer to the plaintiffs, not only the right to graze but to exclude all others including the grantor, subject to certain limited and unsubstantial exceptions.

Oil leases which grant only the privilege to remove oil and gas from transferor's land are frequently held to create the relation of landlord and tenant. The People v. Phillips, 394 Ill. 119, 67 N.E.2d 281 (1946); Spence v. Lucas, 138 La 763, 70 So. 796 (1915); Barnsdall v. Bradford Gas Co., 225 Pa. 338, 74 A. 207 (1909); Duke v. Hague, 107 Pa. 57 (1884). See a full discussion of the nature of oil leases in 1A Summers, Oil Gas (Perm ed) §§ 151 et seq. Similarly, a tenancy is recognized where land is leased solely for mining purposes. Malcomson v. Wappoo Mills, 85 Fed 907 (C C S C 1898); Stinson v. Hardy, 27 Or. 584, 41 P. 116 (1895); Northern Light Mining Co. v. Blue Goose Mining Co., 25 Cal.App. 282, 143 P. 540 (1914); Consolidated Coal Co. v. Peers et al., 150 Ill. 344, 37 N.E. 937 (1894); Head v. Little, 312 Ky. 10, 226 S.W.2d 322 (1950).

A conveyance of land for use as a railroad right of way only has been held to create a corporeal interest. Central Pacific Railroad Co. v. Benity, 5 Sawyer 118 (C.C. Nev. 1878); Tennessee and Coosa R.R. Co. v. East Alabama R'y. Co., 75 Ala. 516, 51 Am State Rep 475 (1883); Alaska Cent. Ry. Co. v. Dooley, 4 Alaska 184 (1910); New York, Etc., R.R. Co. v. Trimmer, 53 NJL 1, 20 A. 761 (1890); Rutland Railroad Co. v. Chaffee, 71 Vt. 84, 42 A. 984 (1898). See, Comment, 30 Or L Rev 380 (1951).

We have already alluded to the case of Springer v. Durette, 217 Or. 196, 342 P.2d 132 (1959), in which the single use of land for grazing was deemed sufficient to constitute possession as a basis for title by adverse possession. If grazing is sufficient to constitute possession as a basis for originating title, it is sufficient to form the basis for the derivative ownership of a possessory estate.

Plaintiffs rely principally upon two Oregon cases distinguishing a lease and a license. In Forsyth v. Nathansohn, 139 Or. 632, 633-638, 9 P.2d 1036, 11 P.2d 1065 (1932), plaintiff brought an action to recover $700 alleged to be due under a "lease" executed to defendant. The instrument upon which action was brought was entitled "Trapping Lease and Option." It was couched in the terms of a lease. The plaintiff "`demised and leased * * * the Trapping Privileges on the following described lands.'" The "lease" was "for Trapping Purposes Only." Defendant covenanted to pay a specified sum "as rent." The instrument further provided that defendant was entitled to the occupancy of a log house located on the premises; plaintiff reserved "`all grazing rights on said lands covered by this lease; and further reserves the right to trap coyotes and wildcats'"; defendant was authorized to assign the "lease" to a named party; plaintiff reserved the right to re-enter upon breach. Defendant's answer, which described the instrument in question as "`a contract for trapping privileges in and around the marsh and lake known as Gray's Lake, Idaho,'" defended on the ground that he was induced to sign the instrument as a result of plaintiff's false representations. During the course of the trial defendant took the position that "[t]he document is a license rather than a lease." On appeal defendant argued that the instrument was a lease but that it was void because it did not definitely describe the land demised. The instrument described the land as "[n]ine hundred twenty-eight and 90/100 acres'" in three designated sections and all of another section, "`a total acreage of 1,568.90.'" Defendant contended that the instrument could not be a lease because it did not locate the 1,568.90 acres in the sections mentioned. To answer this argument plaintiff contended that the instrument was "an exclusive license or privilege to go upon certain described lands for trapping purposes only." Then on rehearing defendant argued that the interest created was a profit a prendre. The court conceded that if the agreement contemplated that the trapping was to be done on the plaintiff's land a profit a prendre would have been created. But the evidence disclosed that the trapping (for muskrats) was to be done in Gray's Lake; plaintiff's land to be used only as a means of access to the water. Faced with the confusion created by the shifting theories advanced by the parties, the court said on rehearing that "since it [the instrument] was reasonably capable of construction as a license, we adopted the construction of it suggested by the defendant in the circuit court and held it a license." The court added, "[w]e still believe that that conclusion is warranted."

We think that the court correctly held that a lease was not created. It seems clear that the parties did not intend that the possession of the 1,568.90 acres was to pass to the defendant. The reservation in the plaintiff of the right to trap and to graze animals quite clearly shows that plaintiff retained control over the premises. The fact that the privilege granted was for a limited type of use only does not, in itself, preclude the finding that a lease was created. But in the Forsyth case, unlike the situation in the case at bar, the transferor expressly reserved the right to graze cattle and to trap the predators which might endanger his herd. Moreover, considering the other possible uses of the land involved, including its use for grazing, the interest granted was considerably more narrow than the interest granted in the case at bar.

The other case relied upon by plaintiffs is Strandholm v. Barbey, 145 Or. 427, 431-441, 26 P.2d 46 (1934). There plaintiff, a gill net fisherman, sought to enjoin defendant from maintaining a wharf and several fish traps which interfered with plaintiff's fishing operations in the Columbia river. Defendant rested his claim to use the river bottom on an instrument executed to him and another by the Secretary of War. The instrument contained the usual language of a lease. The "lease" was "`for seining purposes only.'" It was "`subject to revocation at will by the Secretary of War.'" The premises were described as "`the land on the south side of the Sand Island Military Reservation, * * * as follows: All of that certain premises on the south shore of Sand Island together with rights, easements and appurtenances thereunto belonging, known as Sites Nos. 1, 2, 3, 4, and 5 * * *.'" The instrument contained various provisions relating to lessees' use of the premises; the use and occupation of the premises were subject to "`such rules and regulations as the Commanding Officer, Fort Stevens, Oregon, may from time to time prescribe.'" The instrument recited that the lessees were permitted to erect "`such temporary structures for the housing of their employees, animals, etc. as are absolutely necessary in connection with the seining operations.'" The number, location and dimensions of the structures were subject to the approval of the commanding officer and all work incident to their construction was to be performed under his supervision. There were other restrictions on lessees' use. The defendants contended that they had a leasehold estate in the island which gave them the riparian right to wharf out from the shore line. The court held that the instrument created a license and not a lease. The court held that the authorization to construct the wharf was not a declaration that the grantee could erect a wharf without first obtaining permission from the State of Oregon. It was held that since the title to the bed of the river was owned by the state the lessee had no right to maintain the wharf below low water mark in the absence of a grant of authority to do so from the state. With the decision resting upon this ground it was not necessary for the court to describe the grantees' interest in the upland. The court's reasons for concluding that the grantees had a license only are not convincing. The court said:

"The fact that the questioned rights are to be exercised upon a military reservation; the fact that the right is (1) personal to Barbey and the Columbia River Packers Association; (2) revocable at will; (3) permits the grantees to use the island for a single purpose only; (4) does not confer upon the grantees possession of the island; and (5) the fact that the right conferred stops short of granting to Barbey and his associates an estate in the land convinces us that the instrument creates a license and not a lease." 145 Or at 441.

The fact that the interest was "personal," i.e., nonassignable, or that it was revocable, or that it was for a single purpose does not, as we have shown, preclude the finding that a lease is created. The factors mentioned by the court under (4) and (5) in the quotation simply state the conclusion which the inquiry seeks to test.

Upon a re-examination of Strandholm v. Barbey, supra, we are of the opinion that the interest created there would more aptly be described as a leasehold rather than as a license.

We have found no cases expressly holding that the interest of a holder of a privilege to graze granted under the Taylor Grazing Act is a leasehold interest. However, in Garcia v. Sumrall, 58 Ariz. 526, 121 P.2d 640 (1942), the court assumes that a possessory interest is created in the grantee of a Taylor Grazing Act lease. In that case plaintiffs received a "lease" for one year under the Taylor Grazing Act. Before the expiration of the one-year term plaintiffs made application for a renewal of the lease. After the year term had expired a new lease for five years was delivered to plaintiffs. During the period between the expiration of the old lease and the delivery of the second lease plaintiffs continued to pasture their livestock on the land covered by the lease. Defendants permitted their cattle to graze on these lands and plaintiffs brought an action of trespass. The court held that plaintiffs were "tenants from month to month after the expiration of their lease, and that their possession was good as against everyone except the landlord." 121 P.2d at 643-644. The court did not purport to describe plaintiffs' interest during the term of the executed "lease" but it is evident that the court regarded this interest at that time as that of a lessee with the concomitant right of possession. Other cases involving grazing leases have treated the lessee's interest as an estate in possession. Shreeve v. Greer, 65 Ariz. 35, 173 P.2d 641 (1946) (contract to sell grazing leases held to be specifically enforceable); American Mortgage Co. v. White, 34 N.M. 602, 287 P. 702 (1930) (grazing lease characterized as "chattel real" and held to be assignable in absence of a contrary provision in the lease); Scharbauer v. Graham, 37 N M 449, 24 P.2d 288 (1933) (mortgage of grazing lease held to create a mortgage lien upon a renewal of the lease). See also, Schell v. White, 80 Ariz. 156, 294 P.2d 385 (1956); Epletveit v. Solberg, 119 Mont. 45, 169 P.2d 722 (1946); State v. Vesely, 40 N M 19, 52 P.2d 1090 (1935); Lea County Water Co. v. Reeves, 43 N M 221, 89 P.2d 607 (1939); Mecom v. Gallagher, 213 S.W.2d 304 (Tex Civ App 1947); Sullivan Co. v. Meer, 58 Wyo 90, 125 P.2d 168 (1942). But cf., J.M. Huber Petroleum Co. v. Yake, 121 S.W.2d 670 (Tex Civ App 1938).

Upon the basis of the foregoing analysis it is our conclusion that the interests acquired by the plaintiffs in the present case were possessory in nature and "held under a lease" within the meaning of ORS 307.060.

Plaintiffs contend that even if their interests are regarded as leaseholds, ORS 307.060 is unconstitutional on the ground that it violates the principle of federal immunity from state taxation and on the further ground that it discriminates against the federal government or those to whom its property is leased.

ORS 307.060 does not directly impose a tax upon the federal government; the tax is upon the lessee. In the event that the tax is not paid the leasehold only is subject to foreclosure; the lien does not affect the interest of the federal government in the fee. See United States v. City of Detroit, 355 U.S. 466, 78 S Ct 474, 2 L Ed2d 424 (1958). Cf., United States v. Allegheny County, 322 U.S. 174, 64 S Ct 908, 88 L Ed 1209 (1944). Although a state may not levy a tax directly against the federal government or its property without the consent of Congress, McCulloch v. Maryland, 17 US (4 Wheat.) 316, 4 L Ed 579 (1819), the principle of immunity "does not shield private parties with whom it does business from state taxes imposed upon them merely because part or all of the financial burden of the tax eventually falls on the Government." United States v. City of Detroit, supra, 355 US at 469. The fact that the tax upon the lessee's right to use the land is measured by the "full true cash value" of the land itself does not invalidate the statute. United States v. City of Detroit, supra; United States v. Township of Muskegon, 355 U.S. 404, 78 S Ct 483, 2 L Ed2d 436 (1958). See also, City of Detroit v. Murray Corp., 355 U.S. 489, 78 S Ct 458, 486, 2 L Ed2d 441, 460 (1958).

Plaintiffs' claim of immunity on the ground that they are instrumentalities of the federal government can not be sustained. Plaintiffs use the leased lands for their own private purposes; they do not in any sense represent the government of the United States in making such use. United States v. Township of Muskegon, supra.

Plaintiffs next argue that the imposition of a tax under ORS 307.060 upon lessees of the federal government results in discrimination because lessees holding under any lessor other than the federal government are not subjected to an ad valorem tax. As will be discussed below, ORS 307.110 imposes a similar tax upon lessees of property leased from the state or its subdivisions. Where land is owned by a non-exempt landlord the legislature has seen fit, as a matter of administrative convenience in collecting the tax, to provide for one assessment against the landlord rather than to separately evaluate and assess the interests of the landlord and tenant. Under such a method of assessment the legal incidence of the tax is upon the landlord but the assessment reflects the value of the interests of both landlord and tenant and the burden of the tax eventually falls, in part at least, upon the tenant in the form of higher rent. Hammond Lumber Co. v. County of Los Angeles, 104 Cal.App. 235, 285 P. 896, 898 (1930). The entire interest in the land is subjected to tax, including the interest of the tenant; the tenant's interest is not treated separately for tax collection purposes simply to avoid the expense and inconvenience of a separate assessment. If the landlord's reversionary interest is tax exempt the state may then choose to tax the lessee's separate interest. The lessee should not be permitted to escape the taxation of his interest merely because the reversionary interest of the landlord happens to be tax exempt. De Luz Homes, Inc. v. County of San Diego, 45 Cal.2d 546, 290 P.2d 544 (1955); Hammond Lumber Co. v. County of Los Angeles, supra; San Pedro Etc. R.R. Co. v. Los Angeles, 180 Cal. 18, 179 P. 393 (1919); Keesling, Property Taxation of Leases and Other Limited Interests, 47 Calif L Rev 470, 476 (1959).

Plaintiffs attempt to contrast ORS 307.060 with ORS 307.110 for the purpose of showing that the federal government is discriminated against in the imposition of the ad valorem tax. ORS 307.110 provides in part that "all real and personal property of this state or any institution or department thereof or of any county or city, town or other municipal corporation or political subdivision of this state, held under a lease or rented or held as an oyster claim by any person whose real property, if any, is taxable * * * shall be subject to assessment and taxation for the true cash value thereof uniformly with real property of nonexempt ownerships." ORS 307.060, it will be noted, imposes the tax upon real and personal property of the United States "held by any person under a lease or other interest or estate less than a fee simple." Plaintiffs' argument appears to be that ORS 307.060 taxes interests in land less than a leasehold, whereas ORS 307.110 taxes only leaseholds, with the exception of interests held as an "oyster claim," and that, therefore, there is discrimination against the government of the United States. It will be noted that ORS 307.110, in addition to subjecting leaseholds to taxation, also taxes property "rented * * * by any person whose real property, if any, is taxable * * *." It might be argued that the disjunctive "or" between "held under lease" and "rented" indicates a legislative intent to include under the latter term the renting of interests other than a leasehold, which could include an "other interest or estate less than a fee simple" subject to tax under ORS 307.060. However, it is more likely that the terms "held under lease" and "rented" were intended to relate to the creation of possessory interests and we so interpret the statute.

The question then is whether ORS 307.060 was intended to embrace derivative interests from the federal government other than possessory interests, i.e., to include as being taxable interests easements, profits and other incorporeal interests. Considered separately, the term "or other interest" is broad enough to include non-possessory interest. However, we do not think that the term was used in ORS 307.060 in this broad sense. The statute provides that the interests described "shall be assessed and taxed as for the full true cash value thereof subject only to deduction for restricted use." (Emphasis supplied). We do not think that the legislature intended that one who has a mere incorporeal interest such as an easement or a profit is to be taxed the "full true cash value" of the land with a deduction for the "restricted use." We believe that the statute was intended to apply where the person holding under the United States had an interest of such dignity that it could be regarded as tantamount to a present temporary ownership warranting an assessment of it to him on the basis of its "full true cash value." Certainly the legislature did not intend to impose upon a mere easement holder, for example, an assessment and tax for the full value of the property, subject to deduction for the "restricted use." In such case the restrictions upon the easement holder's use would comprise the entire possessory interest in the land. We construe the statute to include only interests which are capable of possession.

Assuming that we were to interpret ORS 307.060 as including non-possessory interests, still the plaintiffs would not be entitled to attack the statute. We have concluded that plaintiffs held leasehold interests. There is no difference in tax treatment under ORS 307.060 and 307.110 of persons holding leasehold interests. Therefore, plaintiffs would have no standing to attack ORS 307.060 even if it were construed to embrace non-possessory interests because they have not been taxed upon such an interest.

Plaintiffs rely upon Phillips v. Dumas School Dist., 361 U.S. 376, 80 S Ct 474, 4 L Ed2d 384 (1960), in support of their argument that the tax in question is discriminatory. In that case the state of Texas imposed a tax upon premises held by defendants under a lease from the federal government. The court found that under the tax statutes of Texas similarly situated lessees of property owned by the state and its political subdivisions were subjected to a "distinctly lesser burden." Lessees of state land were subject to tax only if the lease was for a term of three or more years, whereas all lessees of federal land, irrespective of the term, were obliged to pay the tax. Further, under the Texas statutes lessees of state lands paid a tax only on the value of the leasehold interest, whereas lessees of federal lands paid a tax on the full value of the fee. Finally, no tax was imposed upon lessees of the state where the lease was terminable at the lessor's option, whereas lessees of lands held under federal leases with such an option were taxed. We find no similar disparities under the Oregon statutes between the burden on lessees from the state or its political subdivisions and lessees from the federal government. Plaintiffs have called to our attention instances in which our statutes specifically exempt from taxation the interest of lessees holding land under a lease from the state: ORS 307.110 (exempting "property leased to or rented by students attending a school or college operated under the direction of the State Board of Higher Education" and exempting leaseholds held by "employes of the state, municipality or political subdivision as an incident to such employment"). ORS 307.120 (exempting real property owned by municipalities and real and personal property owned by ports or dock commissions to the extent to which the property is leased for certain municipal purposes.

The principle that a state may not discriminate against the United States does not require the state in each instance where it enacts a statute exempting from taxation state land leased for certain public purposes to provide a similar exemption for lessees of federal land. It is very likely that in the enactment of most, if not all, of such exemption statutes the exemption did not include land leased from the federal government simply because it did not occur to the legislature that federal lands would be used for the purposes giving rise to the exemption. Moreover, the principle forbidding discrimination does not require a perfect parity of treatment in the taxation of the use of state and federal lands. The tax burden imposed on the users of federal land may be heavier than that imposed on the users of state land if the difference in treatment can be justified. As stated in the Phillips case, "[t]he imposition of a heavier tax burden on lessees of federal property than is imposed on lessees of other exempt public property must be justified by significant differences between the two classes." Phillips v. Dumas School Dist., supra, 361 US at 382. See also, Note, 29 U Cinc L Rev 381 (1960). We hold that the tax provided for under ORS 307.060 which was imposed upon plaintiff is not discriminatory.

The judgment of the lower court is reversed and the cause is remanded with directions to dismiss plaintiffs' complaint.