Solution : https://service.sap.com/sap/support/notes/537783 (SAP Service marketplace login required)
Key words : 
substitution material entered plant, manual product selection, tvsu-suerg reason, manual material substitution, automatic material substitution, entered material, material substitution, tvsu-subar, selected material, substituted material
Related Notes : 
       
| 542537 | Plant determination during material substitution | 
| 378301 | Manual product selection: no plant determination | 
| 377542 | Manual product selection: incorr plant determintn |