• The Contact Hour is a 50 minute unit of an organized learning activity. The contact hour is the official unit of measure of credit by the American Nurses Credentialing Center's Commission on Accreditation (ANCC COA). The Clock Hour is a 60 minute unit of measure of instructional activity. The clock hour is the official unit of measure of credit by the Commission for Case Manager Certification (CCMC). CEUs is a generic term used to indicate continuing education units. It is used by some organizations to denote continuing education credit but is not recognized by the ANCC COA.