Hi Volker,
These GL transaction type will store based upon the posting nature of transaction like.
| Doc No | GL Trans Type | Nature of Postings |
| 1700012 | AZAF | Down payment request |
| 1500025 | AZBU | FI Postings |
| 1500025 | RFBU | Down Payment/Down payment Clearing |
& Also you can refer the Table T022T where you will find certain GL transaction type.
The above posting i checked its behaving like this.
Regd,
Khan.