The base element for a picking route are the output orders. Output orders are created through the class\WMSOrderCreate.
As soon as the WMSOrder is created, it can be attached to a shipment.
If we follow the trace in the wmsOrder.autoAddShipment() we will see the code where the WMSOrderTrans is created.
In the screendump below, we can see where the WMSOrderTrans is created.
Also in the WMSOrder table method ‘addInventTransReservations’ WMSOrderTrans is created
The final step is the creation of the WMSPickingRoute, which happens in the shipment reservation. In this method we also find the creation process for the picking route.
The sequence for creating a picking route is as follows: