Copyright Government of Botswana 
any of the provisions of this Constitution or affect-   (a) the designation, recognition, removal of powers of Dikgosi or Dikgosana   (b) the organization, powers or administration of customary courts;  (c) customary law, or the ascertainment or recording of customary law; or  (d) tribal organization or tribal property, unless-  (i) a copy of the Bill has been referred to the Ntlo ya Dikgosi after it has been introduced in the National Assembly; and  (ii) a period of 30 days has elapsed from the date when the copy of the Bill was referred to the Ntlo ya Dikgosi.  89. Alteration of Constitution   (1) Subject to the provisions of this section Parliament may alter this Constitution.  (2) A Bill for an Act of Parliament under this section shall not be introduced into the National Assembly unless the text of the Bill has been published in the Gazette not less than 30 days before it is so introduced.  (3) In so far as it alters any of the provisions of-  (a) Chapter II; sections 30 to 44 inclusive, 47 to 51 inclusive, and 56; sections 77 to 79 inclusive and section 85; Chapter VII; or sections 117 to 120 inclusive and section 127 in its application to any of the provisions mentioned in this paragraph;  (b) sections 57, 63 to 66 inclusive, 86 to 89 inclusive, 90(2) and (3), 91(2), (3), (4) and (5), and 92; Chapter VI; and section 127 in its application to any of the provisions mentioned in this paragraph, a Bill for an Act of Parliament under this section shall not be passed by the National Assembly unless-  (i) the final voting on the Bill in the Assembly takes place not less than three months after the previous voting thereon in the Assembly; and  (ii) at such final voting the Bill is supported by the votes of not less than two-thirds of all the Members of the Assembly.  (4) In so far as it alters any of the provisions mentioned in subsection (3)(b) of this section no Bill shall be presented to the President for his or her assent unless after its passage by the Assembly it has been submitted to the electors qualified to vote in the election of the Elected Members of the National Assembly, and, on a vote taken in such manner as Parliament may prescribe, the majority of the electors voting have approved the Bill.  (5) In this section-  (a) references to any provision of this Constitution include references to any provision of a law that alters that provision; and  (b) references to the alteration of any provision of this Constitution include references to the amendment, modification or re-enactment, with or without modification, of that provision, the suspension or repeal of that provision and the making of a different provision in lieu thereof. PART V Summoning, Prorogation and Dissolution (ss 90-93) 90. Sessions of Parliament   (1) Each session of Parliament shall be held at such place within Botswana and shall commence at such time as the President may appoint.  (2) There shall be a session of Parliament at least once in every year so that a period of six months shall not intervene between the last sitting of Parliament in one session and the first sitting thereof in the next session.  (3) Whenever Parliament is dissolved a general election of the Elected Members