[Code of Federal Regulations] [Title 21, Volume 9] [Revised as of April 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR1311.35] [Page 144] TITLE 21-FOOD AND DRUGS CHAPTER II--DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE PART 1311_Digital Certificates--Table of Contents Subpart B_Obtaining and Using Digital Certificates for Electronic Orders Sec. 1311.35 Number of CSOS digital certificates needed. A purchaser of Schedule I and II controlled substances must obtain a separate CSOS certificate for each registered location for which the purchaser will order these controlled substances.