A UNITED STATES DEPARTMENT OF COMMERCE PUBLICATION Jr NBS AV Voluntary product Standard L^'V’' PS 14-69 * U.S. JEPARTMENT OF ^COMMERCE 1 * National services, write: Clearinghouse U.S. Department of Commerce Springfield, Virginia 22151 Order NBS publications from: *- Superintendent of Documents Government Printing Office * -f Washington, D.C. 20402 asij^ U. S. GOVERNMENT PRINTING OFFICE : 1970 O - 379-062