This part states the procedure for ordering Standard Reference Materials (SRM's) issued by the National Institute of Standards & Technology. SRM's are used to calibrate measurement systems, evaluate measurement methods, or produce scientific data that can be referred to a common base. NIST Special Publication 260, “Catalog of NIST Standard Reference Materials,” lists and describes the SRM's issued by NIST. SP 260 is periodically revised to include new SRM's and eliminate those that have been discontinued. Between editions of SP 260, supplements are issued that list new or renewal SRM's not listed in SP 260. In addition, these supplements list the fees charged for available SRM's.