Solution : https://service.sap.com/sap/support/notes/526975 (SAP Service marketplace login required)
Key words : 
imrm                        enter function module exit_saplci20_001, create customer exit ci200001, customer exit                exit_saplci20_001 import, general maintenance task list, equipment task lists exist, attached correction instructions correct, component processing customer exit, component                    processing  development class, development class imrm, source code corrections
Related Notes : 
       
| 426953 | Task list components in Release 4.5A - 4.5B | 
| 407413 | Task list components in Release 3.1I | 
| 403701 | New component processing (deactivation) | 
| 401893 | New component processing (Activation) | 
| 398783 | Task list components in Release 4.6C |