Solution : https://service.sap.com/sap/support/notes/337272 (SAP Service marketplace login required)
Key words : 
additional key words co40, variable-size item, alternative item group, material availability check, planned order, production order, requirement quantity, longer correct, implemented note 312077, implement notes 311609
Related Notes : 
       
| 328844 | Variable-size items as parts to be discontinued | 
| 312077 | Discontinued parts for variable-size items | 
| 311609 | CO40:Var.-sze item as part t.b.discont.or alterntve |