The plaintiff prays for a declaratory judgment adjudicating the respective rights and duties of the plaintiff and the defendant School District under ORS 336.260, popularly known as the released time statute. The defendant demurred to the complaint on the ground that it failed to state a cause of action. The trial judge raised a question as to whether an application for a declaratory judgment is demurrable, whereupon counsel for both parties requested the court to make a final determination of the matter upon the record as it then stood. By their stipulation the parties and the court understood that the statute was *111being attacked as nnconstitntional on the ground that it was vague, indefinite and uncertain. The court treated the issue so formed as the justiciable controversy presented to him for determination. From a judgment sustaining a demurrer to plaintiff’s complaint, plaintiff appeals.
OES 336.260 reads as follows:
“336.260 Attendance at religious instruction. Any child attending the public school, on application of his guardian or either of his parents, may be excused from such school for a period or periods not exceeding 120 minutes in any week to attend weekday schools giving instruction in religion.”
The plaintiff notified the defendant in writing that he desired that his two children, then attending West Salem School, should be excused from school attendance for a period or periods not exceeding 120 minutes in any one week for the purpose of receiving religious instruction. The defendant, acting through its Superintendent of Schools, denied plaintiff’s application for the requested release. The superintendent’s action was later ratified by the defendant. Defendant’s demurrer was interposed on the ground that the complaint failed to state facts sufficient to constitute a cause of suit.
In sustaining the demurrer the trial court held that OES 336.260 was fatally defective in that it failed to designate the official or board in the school system to whom the application for released time is to be made, and further, that although OES 336.990 makes the violation of OES 336.260 a misdemeanor, there is nothing in the statutes to indicate who is punishable for a violation of OES 336.260.
We must first decide whether the failure of OES *112336.260 or any other statute to specifically designate the school official or officials to •whom the application for released time is to be made renders the statute void for indefiniteness.
It is axiomatic that the courts cannot in the guise of construction supply an integral part of a statutory scheme omitted by the legislature. State of Oregon v. Davis, 207 Or 525, 296 P2d 240 (1956); State v. Wolf, 17 Or 119, 129, 20 P 316 (1888); ORS 174.010; Crawford, Statutory Construction, § 169. See, City of Athena v. Jack, 115 Or 357, 236 P 760 (1925). As stated in State ex rel Everding v. Simon, 20 Or 365, 373, 374, 26 P 170 (1891):
“* * * Courts cannot supply omissions in legislation, nor afford relief because they are supposed to exist. To adopt the language of Mr. Justice Woods, in Hobbs v. McLean, 117 U.S. 579, ‘when a provision is left out of a statute, either by design or mistake of the legislature, the courts have no power to supply it. To do so would be to legislate and not to construe.’ ‘We are bound,’ said Justice Buller, in Jones v. Smart, 1 T.R. 44, ‘to take the act of parliament as they have made it; a casus omissus can in no case be supplied by a court of law, for that would be to make laws; nor can I conceive that it is our province to consider whether such a law that has been passed be tyrannical or not’; and Mr. Justice Story, in Smith v. Rines, 2 Sumn. 354, observes: ‘It is not for courts of justice proprio marte to provide for all defects or mischiefs of imperfect legislation.’ (King v. Burrell, 12 A. & E. 460; Lamond v. Eiffe, 3 Q. B. 910; Bloxam v. Elsee, 6 B. & C. 169; Bartlett v. Morris, 9 Port. 286.)”
But a statute may be legally complete although the administrative machinery by which it is to be made operative is found elsewhere in the statutes, and the *113implementing statutes may be effective to complete the statutory scheme even though it is necessary in doing so to resort to implication. And so, where a statute is silent as to the manner in which a governmental agency such as a district school board is to carry out the purpose of the statute, it is permissible in determining the nature of the agency’s functions to look at the character of its function as defined in other statutes. State v. Buck, 200 Or 87, 262 P2d 495 (1953); City of Wichita v. Wyman, 158 Kan 709, 150 P2d 154 (1944); 3 Sutherland, Statutory Construction (3rd ed), § 6604. Likewise, where the statute does not specify the agency which is to administer the law it is proper for the court to regard the statute as impliedly allocating the administration of the law to the agency which was created by the legislature to carry out the same type of function with which the statute is concerned. Our statutes are replete with instances in which the legislature has set out various duties which are to be performed or powers which may be exercised in carrying out the school laws without mentioning in the statute the specific agency in the school system which is invested with such powers and duties. In the very chapter in which OBS 336.260 is compiled we find other sections which prescribe conduct without any designation of the school official who is to be responsible for administering the section. OBS 336.160; OBS 336.180.
The school district is the agency which is charged with the duty of carrying out the details involved in the administration of the public schools. The day to day tasks which are incident to the teaching of the pupils, including their daily attendance at school, are left to the school district acting through its superintendent, the various school principals and teachers. *114It would be impossible for the legislature to specify in detail each of the powers and duties which might be performed by the school board or its representatives or to indicate in each instance which official, board or person in the hierarchy of school administration is to perform each function.
From an examination of the entire school code we think that it is clear that the legislature intended that the administration of the released time statute should devolve upon the district school board acting through its representatives. As we shall explain more fully below, the only administrative task involved in carrying out OES 336.260 relates to the orderly functioning of the day to day operation of the school program. That is a task which must be carried out by those who are dealing directly with the problems as they arise in the course of dealing with the pupils and their parents. The administration of OES 336.260 is of this character and the school district and its representatives are responsible for carrying out the purpose of the statute.
We turn then to a consideration of the character of the school board’s powers and duties under OES 336.260. The defendant argues that even assuming that the statute can be construed as vesting in a particular agency the authority to act, nevertheless the statute is invalid for still another reason. It is urged that OES 336.260 vests in the administrative agency an unguided and uncontrolled discretion to determine whether a pupil will be released for religious instruction. Certainly the statute would be unconstitutional if there were no standards against which the school officials’ action could be tested. 1 Davis, Administrative Law Treatise, §§2.07, 2.08, 2.11; Forkosch, Administrative Law, §§ 81-84. But we are *115of the opinion that the statute should not be so construed.
First, we regard the statute as vesting in the pupil’s parent or guardian and not the school officials, the power to determine whether the pupil will spend a part of his school time not exceeding 120 minutes in any week in religious instruction. Obviously the legislature did not intend that the school officials should have any voice in deciding whether a particular pupil should receive religious instruction. It seems equally obvious that it was not intended to invest in the school officials the authority to weigh the respective values of religious and nonreligious instruction and decide whether less than 120 minutes in any one week would be sufficient for a particular pupil’s spiritual needs. The statute must, therefore, be construed as requiring the granting of an excuse upon an application by the parent or guardian.
It does not follow that the school officials have no discretion whatsoever in the course of carrying out the mandate of the statute. The statute is silent with respect to the specific manner in which the school is to adjust its program to the demands of those who wish to have their children released from school. The statute does not say that a parent or guardian can set the time when the child shall be released. Neither does it say that the school officials shall set the time. But a statute is not invalid on the ground of indefiniteness or on the ground that it grants an unguided discretion, merely because it fails to set out the various details necessary to the administration of the statute. There are numerous examples of statutes which impose a duty upon an administrative agency but leave the manner of administering the statute to the administrative agency’s discretion. Some *116of the statutes relating to the function of school districts are cast in this form. ORS 330.150; ORS 330.780; ORS 332.110; ORS 332.200; ORS 336.100; ORS 336.310. School districts in this state have the direct responsibility for the operation of the schools. ORS 336.010 et seq. They may make rules and regulations for the government of the district. ORS 332.330. Scores of details of administration are worked out by the school boards, the principals and the teachers. The statute in question simply adds another of these chores to this list of administrative duties. We are entitled to assume that the legislature, in charging the school officials with the duty of excusing pupils for religious instruction, did not intend that that duty should be exercised without regard to the other functions of the school. The statute must, therefore, be construed to permit the exercise of a reasonable discretion by the school officials in the administration of the statute; not in granting or withholding permission to attend religious instruction, but in determining the time within the school day or school week when the pupil shall be excused. Thus, if it should be determined by the principal of the school that the released time must be made to fall during a study period rather than during an instruction period, or that it must fall upon a certain day of the week, or if any other reasonable regulation is made affecting the granting of excuses for religious instruction, the exercise of such discretion is contemplated by the statute. It would be possible, of course, for a school official to act arbitrarily or to impose unreasonable conditions in acting upon requests for released time. But in such cases the remedy of the aggrieved person is not to strike out the statute granting the discretion, but to force the official, through appropriate legal proceedings, to act reason*117ably. See, Castel v. Klamath County, 56 Or 188, 108 P 129 (1910).
The defendant emphasizes the fact that ORS 336.260 is cast in discretionary language, providing that a child “may be excused.” Reference is also made to the title to the bill which created ORS 336.260 which states that it is a bill “To authorize excusing children attending public schools to attend schools giving religious instruction.” It is argued that since discretion is vested in the governing body of the school the statute must either be held unconstitutional because no standards are provided to guide the exercise of the discretion or, if the statute is regarded as valid, the plaintiff has no remedy because the defendant in denying the plaintiff’s request was simply acting within the authority conferred upon it by statute. Defendant’s argument assumes that under the statute the school authorities are granted the power to wholly preclude a child from religious instruction during school hours.
As we have already indicated, we cannot agree with this position; the excuse must be granted subject to the school’s power to designate the time when the child will be released. In one sense, then, the statute is mandatory — the child must be excused upon a proper application. In another sense, the statute is discretionary in permitting the administrator of the school to adjust the time within which the child will be released.
The fact that the statute states that a child “may be excused” does not preclude the construction we have adopted. If necessary to carry out the intention of the legislature it is proper to construe the word “may” as meaning “shall.” Hubner v. Hubner, 67 Or 557, 136 P 667 (1913); Real Estate Assn. v. Port*118land, 23 Or 199, 31 P 482 (1892); McLeod v. Scott, 21 Or 94; 24 P 1061, 29 P 1 (1891); Kohn & Co. v. Hinshaw, 17 Or 308, 20 P 629 (1889); Springfield Milling Co. v. Lane County, 5 Or 265 (1874). See, Freund, Legislative Regulation, p 225; Crawford, Statutory Construction, § 262. There is a reasonable hypothesis for the assumption that the draftsman of OES 336.260 used “may” to express a mandatory rather than a discretionary function of the school district in releasing pupils for religious instruction. The basic idea in the education code with respect to attendance is expressed in OES 339.010 which states that, subject to certain exceptions, all children between the ages of 7 and 18 years are required to attend a public full-time school. The chapter then sets out certain exceptions to this basic requirement. These exceptions may be viewed as an authorization to the proper school officials to exempt attendance upon a proper showing that the exception applies, i.e., that upon such showing the officials “may” excuse attendance. OES 336.260 is also an exemption from attendance and could well have been drafted in terms of what the school district “may” do in the particular instance, i.e., to relieve the child from the compulsory education provision found in OES 339.010 in the event that application is made for a release of the child for religious instruction.
We regard the statute as stating that a child shall be excused upon the presentation of a proper application for his release. The authority of the school district or its representatives to adjust the time when the child’s absence shall fall in the school day, although not expressed, is derived by implication from the other sections of the school law which delegate to the school district and its representatives the power to operate the schools and to make such regulations as are neces*119sary to do so. See, for example, OES 332.340, OES 336.030, OES 339.030(7), OES 339.010, OES 336.010.
The trial court held that OES 336.260 was unconstitutional on the further ground that a violation of the statute is made a misdemeanor under OES 336.990 and that the person who is subject to penalty for violation of OES 336.260 is not made certain. We shall assume, without deciding, that OES 336.990 is invalid on the ground stated by the trial court. But this is not an action in which the penalty prescribed in OES 336.990 is sought. If, therefore, OES 336.990 and OES 336.260 are severable, the invalidity of OES 336.990 is immaterial; the invalid section may be stricken and the other section, if sustainable as an independent provision, must be sustained. This is clearly the case here. Proof of the independent character of OES 336.260 is found in its legislative history. OES 336.260 was first enacted in 1925 (Oregon Laws 1925, ch 24). Until 1951 no criminal penalty was imposed for the violation of the section. In 1951 the legislature enacted a catch-all penalty provision relating to the sections in the chapter on education of which OES 336.260 (then § 111-3014, O.C.L.A.) was a part. The 1951 penalty statute simply provided that the “Violation of the provisions of title 111, O.C.L.A., for which a specific penalty is not provided is a misdemeanor.”
In the general revision of the statutes in 1953 .the foregoing provision was revised to read as it now does in OES 336.990. It is apparent from the history of the two sections in question that OES 336.260 was intended to have effect as a noncriminal statute long before the penalty section was added.
It is elementary that the unconstitutional part of a statute may be excised without destroying a sep*120arable part of the statute. ORS 174.040. Seale, et al. v. McKennon, 215 Or 562, 336 P2d 340 (1959); Dodd v. State Industrial Accident Commission, 211 Or 99, 310 P2d 324, 311 P2d 458, 315 P2d 138 (1957); Fullerton v. Lamm, 177 Or 655, 163 P2d 941, 165 P2d 63 (1946); State v. Terwilliger, 141 Or 372, 11 P2d 552, 16 P2d 651 (1933); State ex rel. Pierce v. Slusher, 119 Or 141, 248 P 358 (1926).
The principle of separability applies where the part of the statute which must be stricken is a penalty provision. This may be illustrated by reference to two cases. In International & G. N. Ry. Co. v. Anderson County, (Tex Civ App) 174 SW 305, aff’d, 246 US 424, 38 S Ct 370, 62 L Ed 807 (1915), a statute was attacked on the ground that it imposed excessive penalties. The court said, at pages 318, 319:
“* * * The penalty provision of this act being severable, and no penalties being here inflicted, that portion of the act is of immaterial consideration. Railway Co. v. Michigan R. R. Com., 231 U. S. 457, 34 Sup. Ct. 153, 58 L. Ed. 319; Railway Co. v. Garrett, 231 U. S. 298, 34 Sup. Ct. 48, 58 L. Ed. 229.”
A similar pronouncement is made in Grand Trunk Ry. Co. of Canada v. Michigan Railroad Commission, 198 F 1009 (E.D. Mich), aff’d, 231 US 457, 34 S Ct 152, 58 L Ed 310 (1912). There also the statute was assailed on the constitutional ground that it imposed an excessive penalty. In answer to the contention that the entire statute was unconstitutional the court said,' at page 1021:
“ * * * It is sufficient to • say that we havé not before us an action for the recovery of penalties, that the. penalties, are embraced in a section by themselves, and thus plainly separable from the provisions- here involved; and the question of the *121constitutionality of the penalty clause may properly be left to be determined should an effort be made to enforce the same. Wilcox v. Consolidated Gas Co., 212 U. S. 19, 53-54, 29 Sup. Ct. 192, 53 L. Ed. 382; United States v. Delaware & Hudson Co., 213 U. S. 366, 417, 29 Sup. Ct. 527, 53 L. Ed. 836; Grenada Lumber Co. v. Mississippi, 217 U. S. 433, 443, 30 Sup. Ct. 535, 54 L. Ed. 826.”
To the same effect see, Crawford, Statutory Construction, § 243; 2 Sutherland, Statutory Construction (3rd ed), §§2403-2405.
The decree of the lower court is reversed.