The objective of this report is toexamine the process for assigning UINs (uniqueidentification number) at birth and the mechanism forincorporating them into the civil register and includingthem on the physical birth certificate. This report willdiscuss the CRS (civil registration system) and thepractical steps necessary to ensure a system that canestablish the identity of a person and issue a trustedcertificate to attest to his or her civil status. Althoughit may serve as a reference for country-specificdiscussions, the overarching issues are universal. Thisreport is divided into three main sections : 1) Descriptionof the process flow associated with CR (civil registration),with emphasis on birth registration, to lay out a genericset of processes needed for any system, Description andanalysis of UIN structures and 2) Overview, description andanalysis of UIN structures, followed by use cases. 3)Description of necessary steps and good practices forlinking CRS with CIS (civil identification system), usingUINs as a common denominator.