<s>[INST] When was paragraph 20BB inserted in its application to the States of Tripura and Mizoram by the Sixth Schedule to the Constitution (Amendment) Act, 1988? [/INST] Paragraph 20BB was inserted in its application to the States of Tripura and Mizoram by the Sixth Schedule to the Constitution (Amendment) Act, 1988 on 16-12-1988. </s>