On a perusal of the impugned notice, dated, 28.01.2012, I find force in the submission of the learned counsel for the petitioners that the said notice is absolutely vague and is silent about the ground upon which the enquiry is sought to be conducted. As per BSO 15 (18) an assignment can be cancelled by the District Collector in exercise of revisional powers if the Collector is satisfied that there has been a material irregularity in the procedure or that the decision was grossly inequitable or that it exceeded the powers of the officer who passed it or that it was passed under a mistake of fact or owing to fraud or misrepresentation. Therefore, in case the 1st respondent intends to exercise the said power conferred under BSO 15 (18), it is necessary to specify in the show-cause notice the grounds upon which the assignment is sought to be cancelled and the basis for the prima facie satisfaction of the Collector for invoking the powers under BSO 15(18). Apparently, the impugned notice did not contain any such particulars. The said notice is not adequate to enable the petitioners to make an effective representation against the proposed action. Such a vague notice which does not provide a reasonable opportunity of being heard cannot be sustained being in violation of the principles of natural justice. Therefore, the impugned notice is liable to be set aside on that ground alone.