where the number 80064 identifies NAVSHIPS. In view B,  the  number  80091  identifies  the  Naval  Facilities Engineering Command. 3.   The first part of the system command number is a three-digit group number. It is assigned from the Consolidated  Index  of  Drawings,  Materials,  and Services Related to Construction and Conversion, NAVSHIPS  0902-002-2000.  This  number  identifies  the equipment or system, and sometimes the type of plan. In figure 1-1, view A, the number 800 under the NAVSHIP   SYSTEM   COMMAND   NO.   block identifies the plan as a contract plan. 4.   The second part of the system command number is the serial or file number assigned by the supervisor of shipbuilding. Figure 1-1, view A, shows the number 2647537  as  an  example  under  the  NAVSHIP  SYSTEM COMMAND NO. block. 5. The revision letter was explained earlier in the chapter. It is shown under the REV block as A in figure 1-1, view A. Figure 1-8, view B, shows the shipboard plan numbering system that was in use before the adoption of the current system (view A). They two systems are similar with the major differences in the group numbers in the second block. We will explain the purpose of each block in the following paragraphs so you can compare the numbers with those used in the current system. The first block contains the ship identification number. The examples in views A and B are DLG 16 and DD 880. Both refer to the lowest numbered ship to which the plan applies. The second block contains the group number. In view A, it is a three-digit number 303 taken from NAVSHIPS 0902-002-2000 and it identifies a lighting system plan. View B shows the group number system Figure 1-8.—Shipboard plan numbers. in use before adoption of the three-digit system. That system  used  S  group  numbers  that  identify  the equipment or system concerned. The example number S3801 identifies a ventilating system. To use this number, relate it to the proper chapter of an NSTM. Replace the S with the 9 of an NSTM chapter number and drop the last digit in the number. For example, the number  S3801  would  produce  the  number  9380,  or chapter 9380 of the NSTM titled “Ventilation and Heating.” Blocks 3, 4, and 5 use the same information in the old and new systems. Block 3 shows the size of the plan, block 4 shows the system or file number, and block 5 shows the version of the plan. FILING AND HANDLING BLUEPRINTS On  most  ships,  engineering  logroom  personnel file and maintain plans. Tenders and repair ships may keep plan files in the technical library or the microfilm library.  They  are  filed  in  cabinets  in  numerical sequence  according  to  the  three-digit  or  S  group number and the file number. When a plan is revised, the old one is removed and destroyed. The current plan is filed in its place. The  method  of  folding  prints  depends  upon  the type and size of the filing cabinet and the location of the identifying marks on the prints. It is best to place identifying marks at the top of prints when you file them vertically (upright), and at the bottom right corner  when  you  file  them  flat.  In  some  cases construction prints are stored in rolls. Blueprints  are  valuable  permanent  records.  How- ever, if you expect to keep them as permanent records, you must handle them with care. Here are a few simple rules that will help. Keep them out of strong sunlight; they fade. Don’t  allow  them  to  become  wet  or  smudged with oil or grease. Those substances seldom dry out completely and the prints can become unreadable. Don’t make pencil or crayon notations on a print without proper authority. If you are instructed to mark a print, use a proper colored pencil and make the markings a permanent part of the print. Yellow is a good color  to  use  on  a  print  with  a  blue  background (blueprint). Keep prints stowed in their proper place. You may receive some that are not properly folded and you must  refold  them  correctly. 1-10