Under Section 31, orders and decisions of the Authority are authenticated by the signature of the Chairperson or an authorised member, whereas OTHER instruments executed by the Authority are authenticated by:

Section 31 draws a clear functional distinction: 'orders and decisions' (the Authority's substantive determinations) must be authenticated by the Chairperson or an authorised member's signature, while 'other instruments' (such as deeds, agreements, or documents executed in the course of routine business) are separately authenticated by the signature of an authorised OFFICER of the Authority - not necessarily a member or the Chairperson. This bifurcated authentication scheme allows day-to-day instrument execution to be delegated to competent officers while reserving formal orders and decisions for member-level authentication, and it operates independently of the common-seal requirement under Section 21 for specified contracts.