Solution : https://service.sap.com/sap/support/notes/572758 (SAP Service marketplace login required)
Summary : 
      SAP Note clarifies that custom routines added for customer requirements can be overwritten during upgrades. This involves VOFM routines used in data transfer processes, particularly routines #99, #701, and #702. Due to SAP employing these numbers in customer namespace, users are advised to transfer any modifications to alternate routines (#3, #501, #502) to avoid loss of custom code. Furthermore, necessary adjustments must be made in all relevant configurations to incorporate these changes. This ensures continuity and functionality post-upgrade. Precautions are stressed for preserving valuable custom developments.
Key words : 
customer namespace arenumber 99, orders solution caution, similarly requirement routines 701, requirement routine, requirement routine # 99, code added, overwrittenwhile upgrading, terms rv45te99, data transfer, ata spec2000
Related Notes : 
       
| 356737 | Customer name range for VOFM routines |