Solution : https://service.sap.com/sap/support/notes/110311 (SAP Service marketplace login required)
Key words :
choose 'structural enhancement customer reserve, additional key words vkm1, activate function user exits, system displays error message, activate function 'allowed fields', start transaction vokr, changing ddic objects, change ddic objects, include member dbkmvf02, customizing transaction considers
Related Notes :
| 779389 | VKM*: Extend list with user-defined fields |
| 425581 | Advice note collection: Release, lists |
| 111425 | Fields of VBKRED not filled CMKUA |