Transaction Flow

MTL_TRANSACTIONS_INTERFACE table is the Interface between non-Inventory applications and the Inventory  Transactions module.  In other words any other module other than Inventory that wants to update  Inventory has to come  through this table. Modules such as WIP (Work In Progress)  and OE (Order Entry) first pass their records to the  MTL_TRANSACTIONS_INTERFACE (MTI)for validation.

There is an Interface Manager called the Transactions Manager (INCTCM) which  reads records from this table, validates them and moves the successful  transactions onto MTL_MATERIAL_TRANSACTIONS_TEMP, and submits Transaction workers (sub-processes – INCTCW) which then processes these records through inventory. This process consists of data derivation, validation, and transfer of records from MTL_TRANSCTIONS_INTERFACE, MTL_TRANSACTIONS_LOTS_INTERFACE and MTL_SERIAL_NUMBERS_INTERFACE  into their respective TEMP (temporary) tables from where the transactions  processor processes them.
Both the Lots and Serial number tables above are used when items being  updated are under ‘Lot’ or ‘Serial’ number control. Example :- In the case  of an Sales Order, the item is being shipped to a client so the lot and serial  number if being used, this needs to be updated to show that it is no longer available in Inventory stock.
It is important to note that in general the processors will not move the transactions from this table if the following fields are not set as follows.
LOCK_FLAG = 2
PROCESS_FLAG = 1
transaction_mode = 3
Once the transactions have been passed to this table after initial validation by the Transactions Manager (INCTCM) from the MTL_TRANSACTIONS_INTERFACE a job id is attached and a Transactions Worker (INCTCW) is submitted by the INCTCM process in order to the get the records processed and moved to the MTL_MATERIAL_TRANSACTONS table.
This table is also used by Inventory Module and Purchasing module which writes directly onto this table for any transactions entered within itself and each transaction in turn through a process of strict validation.
Inventory Module Forms like Miscellaneous transactions writes directly into this table. The transactions which are done through these form are on-line processing. It is from here that the inventory quantities finally  get updated,serial/lot numbers get marked as being used.