Solution : https://service.sap.com/sap/support/notes/494284 (SAP Service marketplace login required)
Key words : 
/component data element/component typeactime char1 char1, desired delivery date, apo backorder processing, confirmation schedule line, backorder processing, sales order, requested time, terms actime, bop reason, program error
Related Notes : 
       
| 500500 | Backorder process.: Confirmat. schedule line to the second | 
| 494270 | Backorder processing: R/3 ACTIME | 
| 494015 | No exact-to-second transfer of confirmed schedule lines | 
| 494005 | Changed confirmation time is not transferred | 
| 375193 | Backorder processing: Composite SAP note on posting |