Solution : https://service.sap.com/sap/support/notes/114028 (SAP Service marketplace login required)
Key words : 
tabname      posnr   prtext    objsub           5   alter table r3t01data/objsub    objsub           6   add variant char, alter table r3t01data/objsub       add, default    objsub           7   add workflow char, activated additional key words sql-199, sql statement alter table, tabname = 'objsub'           order, objsub           9   commit    objsub          10, alter table statement, tabname = 'objsub', alter table
Related Notes : 
       
| 102950 | Additional Info: Upgrading to 3.1I DB2/400 |