Lahiri, J.:- This writ application is projected against an order of the Board of Revenue, Governed by the Assam Board of Revenue Act, 1962, in Revenue Appeal No. 30 of 1973. The petitioners claim that the sole Respondent of the Revenue Appeal Md. Ali Box, husband of petitioner No. 1 died on 23.10.72. The appeal was filed on 6.2.73 about 3½ months after his death. The appellant therein (Respondent No. 2 in the writ application) filed an application for substitution and obtained an order on 27.7.73 long before the petitioners were brought on records permitting the petitioners to be substituted in place of Md. Ali Box. It was violative of the mandatory provisions of Clauses 19 and 20 of the Assam Board of Revenue Regulation, 1963 for short "the Regulation". As such, the order permiting the petitioners to be substituted as legal heirs and representatives of the sole respondent was without jurisdiction. The present petitioners, who were substituted, raised objections that it was beyond the competence of the Board of Revenue to substitute the legal heirs of the sole respondent beyond the period of 90 days provided under Clauses 20 of "the Regulation". The petitioners have stated that there was no application under Clause 23 for setting aside abatement. The order dated 27. 7. 73 allowing the substitution of the sole respondent was rendered "exparte." Thereafter, the petitioners appeared, raised objection and the Board of Revenue passed the final order on 31.1.75, which we quote herein-below :- "31.1.75: Seen petition submitted by the Advocate for praying substi­tution one minor daughter, Azima Begum who was left-out through ignorance and adding the name of Abdul Karim against the entry 4-A male baby'. Also heard Advocate for the Respondent opposing the substitution. As other heirs and successors are already substituted, the present petition is allowed. Let notice be served on the new substitution. Fix. 7.3.75 for service and return of Notice." The jurisdiction of the Board of Revenue to hear and dispose of an appeal is circumscribed by the provisions contained in "the Regulation". Clause 20 prohibits the Board to hear and dispose of an appeal on merits, unless on the death of the Respondent his legal heirs are substituted in accordance with the provisions of the Regulation as the appeal abates. The limitation for substitution is only 90 days from the date of death of a Respondent. Clause 20 prohibits the Board to hear and dispose of an appeal on merits, unless on the death of the Respondent his legal heirs are substituted in accordance with the provisions of the Regulation as the appeal abates. The limitation for substitution is only 90 days from the date of death of a Respondent. Admittedly the substitution was beyond the period of 90 days. There was no application for setting aside abatement. As such, the order of substitution was violative of Clause 20. Under these circumstances, the impugned order must be held to be without jurisdiction, void and invalid. The impugned order is not a reasoned one. There is no reason why the objections of the petitioners were turned down nor is there any indication that the Board of Revenue applied its mind to Clauses 19 to 23 of "the Regulation." Under these circumstances, we are constrained to hold that the impugned order must be set aside. However, it will be open to Respondent No. 2 to take resort to clause 23, for setting aside abatement, if so advised. If such an application is made under Clause 23 of "the Regulation" the learned Board of Revenue shall dispose of the application in accordance with law. In the result, the impugned order dated 31. 1. 75 is set aside and the matter is remitted to "the Board" for due disposal of the application of the petitioners in accordance with law. The petition is allowed with costs of Rs. 200/- payable by Respondent No. 2 to the petitioners. The Rule is made absolute.