I need to understand the accounting entries generated by a sale on stock accounts:

As an example below are the 6 entries generated by one single POS transaction

**02/04/2014    PosLigne3225    Picking:00502       355200 ACCESSOIRES              STJ/2014/3067   0,00    17,28   
    02/04/2014  PosLigne3225    Picking:00502       355202 ACCESSOIRES OUT          STJ/2014/3067   17,28   0,00**  
    02/04/2014  PosLigne3225    IN/00268                355202 ACCESSOIRES OUT              STJ/2014/3066   0,00    17,28   
    02/04/2014  PosLigne3225    IN/00268                355200 ACCESSOIRES              STJ/2014/3066   17,28   0,00    
    02/04/2014  PosLigne3225    **IN/00268**        355200 ACCESSOIRES               STJ/2014/3066  17,28   0,00    
    02/04/2014  PosLigne3225    **IN/00268**        355202 ACCESSOIRES OUT           STJ/2014/3066  0,00    17,28

Specifically, I do not understand what parameter is triggering the entries with the description IN/00268! The account 355200 is the stock account; and 355202 is the account supposed to record the deliverues to customers. Thanks for the masters in the accounting for stocks with OpenErp to try to explain what is wrong with my settings.