Based on the provided directly follows graph for each object type, here's a description of the underlying process:

1. **Customer Order**
   - The process begins with a "Register Customer Order" event.
   - A "Create Transport Document" event follows, indicating that a transport document is created for the registered order.

2. **Transport Document**
   - After the transport document is created, a "Book Vehicles" event occurs, suggesting that vehicles are booked for the transport.
   - Following vehicle booking, "Order Empty Containers" is triggered to acquire empty containers for the transport.
   - The process then diverges into two main paths:
     - The first path involves a "Depart" event, indicating that the transport has started. This event can also be preceded by a "Reschedule Container" event, suggesting that there might be some rescheduling activities before the transport departs.
     - The second path involves a "Reschedule Container" event, which can lead back to "Order Empty Containers" or "Depart", indicating that there might be some adjustments or delays in the transport process.

3. **Container**
   - The process for containers starts with "Order Empty Containers" or "Pick Up Empty Container" events, suggesting that empty containers are ordered or picked up.
   - After acquiring empty containers, the "Load Truck" event occurs, indicating that containers are loaded onto a truck.
   - The process then diverges into two main paths:
     - The first path involves a "Drive to Terminal" event, followed by a "Weigh" event, and then either "Place in Stock" or "Bring to Loading Bay". This path suggests that containers are transported to a terminal, weighed, and then either placed in stock or moved to a loading bay for further processing.
     - The second path involves a "Load to Vehicle" event, followed by a "Depart" event. This path suggests that containers are loaded onto a vehicle and then transported.
   - There's also a possibility of "Reschedule Container" events, which can lead back to "Load to Vehicle" or "Book Vehicles", indicating that there might be some rescheduling activities in the process.

4. **Truck**
   - The process for trucks starts with a "Load Truck" event, indicating that containers are loaded onto the truck.
   - After loading, the truck can either "Drive to Terminal" or "Load Truck" again, suggesting that the truck can either proceed to the terminal or load more containers before moving.
   - If the truck "Drives to Terminal", it can then "Load Truck" again, indicating that it might pick up more containers at the terminal before departing.

5. **Vehicle**
   - The process for vehicles starts with a "Book Vehicles" event, suggesting that vehicles are booked for transport.
   - After booking, the process diverges into two main paths:
     - The first path involves a "Load to Vehicle" event, followed by a "Depart" event. This path suggests that containers are loaded onto the vehicle and then transported.
     - The second path involves a "Reschedule Container" event, which can lead back to "Load to Vehicle" or "Book Vehicles", indicating that there might be some rescheduling activities in the process.

6. **Forklift**
   - The process for forklifts involves various events related to moving containers between different locations, such as "Bring to Loading Bay", "Load to Vehicle", "Weigh", "Place in Stock", etc. These events suggest that forklifts are used to move containers between different areas in the process.

7. **Handling Unit**
   - The process for handling units starts with a "Collect Goods" event, indicating that goods are collected for transport.
   - After collecting goods, a "Load Truck" event occurs, suggesting that the collected goods are loaded onto a truck for transport.

In summary, the underlying process involves the following key steps:

- Registering a customer order
- Creating a transport document for the order
- Booking vehicles and ordering empty containers for the transport
- Loading containers onto trucks and vehicles
- Transporting containers to terminals or other destinations
- Weighing, stocking, and moving containers using forklifts
- Rescheduling containers if necessary
- Departing with the transported containers

The process involves multiple object types and their respective events, with some events leading to different paths, suggesting that there might be variations or exceptions in the process.