69 and in either case the Speaker must cause the Bill to be presented to the President without delay for assent and signature and must give public notice of the date on which the Bill was sent to the President. (8) If a Bill that has been presented to the President in terms of subsection (7) fully accommodates the President’s reservations, the President must assent to the Bill and sign it within twenty-one days and then cause it to be published in the Gazette without delay, but if the President still has reservations about the Bill, he or she must within that period either— (a) assent to the Bill and sign it, despite those reservations; or (b) refer the Bill to the Constitutional Court for advice on its constitutionality. (9) If on a reference under subsection (8) the Constitutional Court advises that the Bill is constitutional, the President must assent to it and sign it immediately and cause it to be published in the Gazette without delay. (10) If a Bill is presented to the President for assent and signature and it is not accompanied by a certificate which is required by any provision of this Constitution, the President must not assent to the Bill or sign it until the certificate is produced but must cause the Clerk of Parliament to be notified, immediately and in writing, that the certificate was not sent with the Bill. 6.17 Commencement of Acts of Parliament An Act of Parliament comes into operation at the beginning of the day on which it is published in the Gazette, or at the beginning of any other day that may be specified in the Act or some other enactment. 6.18 Enrolment of Acts of Parliament (1) When the President has assented to and signed an Act of Parliament, the Clerk of Parliament must transmit a fair copy of it, authenticated by the President’s signature and the public seal of Zimbabwe, to be enrolled in the office of the Registrar of the High Court, and that copy is conclusive evidence of the provisions of the Act unless the Act is revised under an Act of Parliament referred to in subsection (2). (2) An Act of Parliament may provide for the statute law, or any part of it, to be published in revised form and may further provide that (a) upon being published, the revision is the sole authentic version of the statutes contained in it; (b) a copy of the revision must be deposited in the office of the Registrar of the High Court; and (c) the copy that is deposited in the office of the Registrar of the High Court is conclusive evidence of the provisions of the statutes contained in it. (3) The validity of an Act of Parliament or a revision of the statute law does not depend on its enrolment or deposit under this section.