Solution : https://service.sap.com/sap/support/notes/384768 (SAP Service marketplace login required)
Key words : 
change item data  xxxx xx   0050, additional key words cs20, variable-size item quantity, variable-size items, material xxxx changed 2, 'corrections' -> 'correction instructions', advance corrections ensures, item change, advance corrections, changed quantity
Related Notes : 
       
| 436538 | New CS20: Log quantity 1 piece ---> 0 pieces | 
| 397826 | CS20: Component quantity change without component unit | 
| 379633 | New CS20: change component unit of measure | 
| 216564 | CS20: Changing and deleting BOMs w. history req. | 
| 216044 | CS20: No RC29P-MENGE field or entry not allowed | 
| 180686 | CS20: Basic note for new version |