a  mandatory  government  source  of  supply.  The mandatory  sources  are  as  follows: Defense/federal  supply  systems  for  material assigned  an  NSN Excess personal property from other agencies Federal prison industries National  industries  for  the  blind  or  other severely  handicapped Mandatory   GSA   federal contracts Optional  GSA  federal contracts supply   schedule supply   schedule OPEN  MARKET  PURCHASES The methods for making small purchases and corresponding  dollar  limitations  are  as  follows: Small  business-small  purchase  set-aside.  Each purchase  with  small  business  concerns  must be  $10,000  or  less. Blanket   purchase   agreement   (BPA).   Each BPA   call   may   not   exceed   $10,000   (except $25,000  for  inventory  control  points  [ICPs]) with  an  unlimited  amount  for  subsistence. Imprest  fund  (IF).  Each  purchase  using  the  IF may  not  exceed  $500. Purchase order. Each purchase order may not exceed  $25,000. Purchase  invoice.  The  purchase  invoice method using the Standard Form 44 may not exceed  $2,500  (except  $10,000  for  aviation  fuel and  oil  purchased  by  pilots). SMALL  PURCHASE  PROCEDURES A purchase request (PR) must be prepared and approved  before  the  contracting  officer  starts  a purchase  action.  A  PR  includes  the  various MILSTRIP  requisitions,  a  Request  for  Contrac- tual  Procurement,  NAVCOMPT  Form  2276,  or the  Military  Interdepartmental  Purchase  Request, DD  Form  448. Purchase  Request All  PRs  received  must  be  receipt  dated, screened,  routed  for  recording,  and  assigned  a control  or  route  sheet.  The  initial  screening includes   an   authorized   signature;   accounting information; a priority designator and a required delivery  date;  clearance  and  approval;  and  an attached  statement  of  work,  technical  specifica- tions,  drawings,  or  blueprints. A  final  screening  of  all  PRs  is  conducted  by the  buyer  or  storekeeper  for  adequacy.  When  a PR is determined to be inadequate, it is returned to the originator for modification or cancellation. Each contracting office establishes minimum standards  for  requirements  data  that  must  be included  as  a  part  of  each  PR  before  it  is considered  adequate.  The  minimum  level  of information  needed  to  determine  adequacy  should include,  but  not  necessarily  be  limited  to,  the following: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Funding Plain English (adequate purchase descrip tion  or  specification  or  statement  of  work) Part  number  and  corresponding  CAGE code Quantity Required delivery date or period of per- formance  and  priority  designator Place  of  delivery  with  proper  consignment instructions,  if  applicable Previous  buys  and  prices  paid  for  the same or similar item or, when no history exists, a price estimate and the basis upon which the estimate was established Sole  source  justification,  if  required A   point   of   contact   for   technical information Any unique requirements such as mark- ing,  packing,  or  transportation  account- ing  codes Document   number Funding of Purchase Request The  estimated  cost  shown  on  the  PR  is  the amount  committed  by  the  requiring  activity  to cover   the   purchase   of   supplies   or   services. Responsibility  for  controlling  the  obligation  of funds and the limitations of such funds is vested exclusively in the allotment holder or designated representative.  However,  this  does  not  relieve  the contracting officer from complying with purchas- ing  regulations  contained  in  the  SUPARS.  The 4-2