The dataflow as functional process below are the points:

1) Purchasing Requsition -> sent by inventory dept to purcharsing dept
2) Request for Quotation(RFQ)-> Purchasing Dept shall ask the vendors to give the quotation for the requested materials by inventory.
3) Quotation -> Quotation is sent by vendors to the company
4) Purchase order-> Based on all paramers of a quotation sent by vendors. Vendors are selected from whom the material has to be obtained.  The company  gives  purchase order to the vendor.
5) Good's receipt -> vendors sends the goods to the company with goods receipt
6) Invoice verification ->  this done based on good's receipt. this means that the ordered goods have reached or not.
7) Payment -> payment is done based on invoice verification. this is (FI/CO)   *-- Santosh Kumaar.M

Full MM Transaction Codes Flow:

RFQ to Vendor - ME41
Raising Quotation - ME47
Comparison of Price - ME49
Creation of PO - ME21N
Goods Receipt - MIGO
Invoice (Bill PAssing) - MIRO
Goods Issue - MB1A
Physical Inventory - MI01( Create doc)
MI04 (Enter Count)
MI07 (Post)

The FI - MM integration:

First you define the g/l master records.
1) Inventry raw material a/c
2) GR/IR clearing a/c
3) Raw material consumption a/c
Above like this you define all required g/l accounts then you will go to T.CODE - OBYC 
Double click BSX (this is transaction key)
      "            GBB
      "            WRX
      "            PRD
These are transaction keys important.
Then you go to T CODE - OMSY (this is also important) then 
  Material creation T Code MM01 
  then 
1) Purchase order T.code  ME21N
2) Goods received     "       MIGO
3) Invoice verification  "      MIRO

The FI - MM integration finished.  *-- Vadlamudi

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