open-reel tapes and will help eliminate tape cling. All tapes should be cleaned and certified annually. CERTIFICATION. —Tape certification requires the use of a tape certifier machine. A tape certifier performs digital and analog evaluations of a tape against a calibrated standard. The objective of the certifier is to exercise the tape far in excess of the operational requirements of its tape unit. The tape certifier checks the ability of the tape to record  high-density  data,  to  retain  magnetic  flux patterns,  and  to  be  demagnetized.  The  certifier performs tape cleaner functions before testing the tape. It also leaves the tape completely erased after testing. Tapes that are certified error free to a particular density will,  in  all  probability,  give  months  of  error-free performance. Tapes that cannot be certified should be destroyed. DEGAUSSING. —A degaussing machine  is in effect  a  big  tape  eraser.  The  machine  applies  an at-induced  electromagnetic  field  of  varying  strengths to  the  tape.  The  field  completely  nullifies  all  the magnetic flux patterns stored on the tape. Degaussing provides for a complete erasure of all information stored on a tape. It maybe used to remove classified data from tape as specified in the  ADP Security Manual, DOD 5200.28-M, sections VII and VIII. STRIPPING. —Magnetic tape tends to show the greatest wear on the portions of the tape immediately following the BOT marker. Seldom is an entire tape reel used to store data; only a third of the tape or less is used for storing data inmost applications. Excessively worn or damaged areas of tape maybe stripped (cut away) from the reel, and a new BOT marker installed on the tape. Stripping is a useful tool for those installations that do not have tape cleaners or certifiers available. NOTE: Do not strip open reels down to less than 500 feet of tape, since the remaining usable storage area is limited. Standard reels containing less than 500 feet of tape should be discarded. SPLICING.  —Taping  together  two  broken  ends  of tape to make one tape is called splicing. Splicing is not recommended for the following reasons: Tape splices are generally the weakest point on the tape and could separate during operation Read and write operations may not perform properly in the area of a splice; tape splices may appear as bad spots on tape Splicing a broken tape usually does not save the data stored on the tape Open-reel tapes that break may be stripped to the break and have anew BOT marker installed. This way the remaining tape on the reel maybe used effectively. Discard cartridges or cassettes that have tape breaks. Tape  Control Of major importance to you as a technician is the amount  of  attention  paid  to  the  control  of  magnetic tapes. Nothing is more embarrassing or potentially destructive  than  the  loss  of  the  last  copy  of  a maintenance program, operational program, or data file. The least problem such a loss could cause would be the time lost in regenerating or acquiring anew copy of the program or data. The worst problem that could result would be the degradation of a major tactical system or capability when needed the most. Tape control can be divided into the following areas: Tape  inventory Program master/working copies Identifying and correcting problems with tapes TAPE INVENTORY.  —Each tape, cartridge, or cassette  used  in  a  system  must  be  accounted  for  by number and have its contents identified by a label. A tape label should contain the system location, program or data designation, unit used to generate the tape, security classification, and date the tape was written. For  tapes  containing  more  than  one  program,  a complete listing of all programs, data files, and so forth, should be included in the label. A   written   inventory   should   be   maintained indicating programs or data stored on each tape and the security  classification  of  the  tape.  Tapes  containing classified  information  retain  their  security  classification until properly degaussed or the tape is destroyed. P R O G R A M      M A S T E R / W O R K I N G COPIES. —Tapes, cartridges, and cassettes generally enter a computer system in one of three states: New (blank and certified) Used (cleaned, blanked, and certified) 9-4