Structuring reference numbers
The reference number is defined in the following fields:
- Fixed Part
 - Date Format
 - First Free Number
 
The reference number can consist of:
- Fixed Part / Date / Sequence Number
 - Fixed Part / Sequence Number
 - Date / Sequence Number
 
Reference numbers always consist of 14 positions. The sequence number occupies the positions that are not occupied by the Fixed Part and/or Date.