DD  cannot  accept  requisitions  directly  or  issue stock without the prior authorization of the DSC. The principal DDs are located in Mechanicsburg, Pennsylvania;   Memphis,   Tennessee;   Ogden, Utah;  and  Tracy,  California. Specialized Support Depots Because   of   the   large   number   of   afloat customers, the DLA has established two SSDs to provide direct support to the Navy. The two SSDs are  the  Navy  supply  centers  at  Norfolk  and Oakland.  The  SSDs,  unlike  the  DDs,  have  the authority  to  receive  requisitions  directly  and  to make  issues  locally.  The  inventory  held  at  each depot is, however, owned and managed centrally by  the  cognizant  DSC. NAVY  SUPPLY  SYSTEM As  was  mentioned  at  the  beginning  of  the chapter, the Navy supply system is integrated with the  Defense  Logistics  Agency  system.  The  mis- sion,   organization,   and   functions   of   the   com- ponents of the Navy system are described below. Like  the  DLA  system,  there  are  inventory managers  (the  inventory  control  points),  a distribution system (NSCs, NSDs), and a central headquarters (NAVSUP). The following diagram is  a  comparison  of  the  two  systems: NAVAL  SUPPLY  SYSTEMS COMMAND The Naval Supply Systems Command (NAV- SUP)   supervises   the   provisioning,   cataloging, inventory   management,   distribution,   materials handling,   traffic   management,   transportation, packaging,  preservation,  receipt,  storage,  issue, and  disposal  of  Navy  supplies  and  material,  ex- cept for those items specifically assigned to other systems   commands   or   offices.   Although   NAV- SUP relies heavily on the other systems commands for  technical  advice  concerning  equipment  and material  requirements,  it  also  furnishes  supply management  methods  and  guidance  to  commands and  offices  that  request  management  assistance in  supply  functions. NAVSUP is also responsible for the develop- ment and supervision of the Navy supply system. It must combine all supply and distribution func- tions into one system so that the system can meet the objective of responsive and efficient material support  to  the  operating  forces.  This  is  not  a simple  task.  The  Navy  supply  system  must  be responsive  to  all  levels  of  command  and  must operate at all levels. It is not enough to develop only  those  capabilities  that  will  enable  a  supply system  to  meet  the  needs  of  one  ship,  one  task force, or one fleet. The Navy supply system must be able to respond to all the needs of the operating forces  and  of  their  related  support  activities. As you read the following sections, you should recognize  how  many  supply  functions  are  inter- related so that the Navy supply system can sup- port  your  ship  or  any  other  component  of  the operating forces. You should also determine how your  supply  department,  afloat  or  ashore,  func- tions in much the same way in meeting the needs of a ship or a station. The basic elements of supply support,  for  one  ship  or  for  the  entire  Navy, involve  the  determination  of  requirements,  pro- curement,  and  distribution. Determination of Requirements Determining  requirements  for  material  should not be new to you as you have probably already had some experience in this area aboard your ship. In  performing  this  job,  you  have  had  two  excellent tools  to  work  with—the  Coordinated   Shipboard Allowance List (COSAL) and the usage data from your stock record cards. The COSAL is discussed later in this rate training manual and in Military Requirements  for  Petty  Officer  Third  Class through   Chief  Petty  Officer.  The   Navy   supply system  uses  the  COSAL  and  stock  record  cards for  determining  the  requirements  for  replenish- ment materials. However, not all material comes under  the  heading  of  replenishment.  When  new material,  such  as  the  repair  parts  requirement for   a   newly   developed   item   of   equipment,   is 2-3