56.(1) The powers exercisable by a Collector under Chapter IV and Chapter V and under clause (a) of the first proviso to section 26 shall in all cases be subject to the control of the Chief Revenue-authority.(2) If any Collector, acting under section 31, section 40 or section 41, feels doubt as to the amount of duty with which any instrument is chargeable, he may draw up a statement of the case, and refer it, with his own opinion thereon, for the decision of the Chief Revenue-authority.(3) Such authority shall consider the case and send a copy of its decision to the Collector, who shall proceed to assess and charge the duty (if any) in conformity with such decision.