This Technical Paper is a condensed version of the Conference Room document prepared by Nora P. Powell, IIVRS Consultant, 21st Session of the United Nations Statistical Commission held 12-21 January 1981 in New York. It is based on the problems perceived and reported in response to a survey conducted by the IIVRS.The article is technical report No. 15 of the International Institute for Vital Registration and Statistics (IIVRS), published in 1981.