ji nahi , now i will explain u in detail . cast certificate are of two type one is state and other is central. consider an example of " meena " cast which is under OBC in rajasthan but same caste will treated as general in Madhyapradesh .To avail the benefit of reservation in central govt job or instittue u shud have central govt certificate . ur caste certificate is valid only in Assam. to avail benfit in central govt job , just go to SDM or collector office along with ur state caste certificate and print copy of this annexure . they will sign on this certificate and u have done.