What is movement type ?
In SAP every movement of goods(physical/non-physical) needs to be documented.
The types of movement for which movement types are used are

1. Good Reciept
1. Vendor
2. Production
   
2. Goods Issue
1. To Customer
2. To Production
   
3. Stock Transfer
1. From one Storage Location (SL) to another within the same plant or different plants.
   
4. Transfer Posting
1. A generic terms for stock transfers(physical) or changes in stock type /category(non-physical) of a material. For example, from SAP's perspective one material could be converted to anothe , or material is released from quality to WH etc

All the goods movement types discussed above lead to one of the 2 types of documents described below. ( Its a generally accepted norm in accounting that all goods movement be documented)

1. Material Document
2. Accounting Document
   
1. Created only when the corresponding movement type is associated with G/L A/c update.
   
2. Multiple A/C documents can be created for a single material document(depending on the items and movement in the Mat. document).

Apart from creating the material and A/C documents , the stock quantities/stock values are updated and the appropriated G/L a/c's updated based on whether the goods movement is related to value updation of quantity updation. For each goods movement/special stock indicator combination , if value/quantity/both needs to be updated are specified in OMJJ.

Important notes on material/accounting documents

1. Once posted they cannot be changed
2. To modify a posting , another reverse posting has to be created.
   

It is done through material document(change/view through MB02/03. Created automatically via goods movement). There could be different types of movements possible and SAP defines pre-defined movement types and associate all the characterstics of the movement to the Movement Type. For example it can be specified it the type of movement is Stock transfer or inventory correction or returns..etc. Also the valuation changes (If the material is based on value, then the appropriate G/L A/Cs are updated becuase of the movement ) are posted automatically.
Tcode : OMJJ (spro>IMG>MM>Inventory Management & Physical Inventory>Movement Type> Copy change Movement Type)