Below there is a Python code that implements a Partially Ordered Workflow Language (POWL) model representing the "Purchase-to-Pay" process:

```python
import pm4py

from pm4py.objects.powl.obj import StrictPartialOrder, OperatorPOWL, Transition, SilentTransition

from pm4py.objects.process_tree.obj import Operator

# Each stage of the process is represented as a Transition with specific actions
order_confirmation = Transition(label="Receive Order Confirmation")
validate_order = Transition(label="Validate Order")
place_order = Transition(label="Place Order")

# Used for actions like cancellation or verification that are optional stages of the process
cancel_order = SilentTransition()
verify_order = SilentTransition()

# Stages within the process, using XOR or LOOP operators
order_process = OperatorPOWL(operator=Operator.XOR, children=[order_confirmation, validate_order])

order_placement = OperatorPOWL(
    operator=Operator.LOOP,
    children=[place_order, cancel_order]
)

order_execution = OperatorPOWL(operator=Operator.XOR, children=[verify_order, order_placement])

# Root of the process, aggregation of all steps
flush_process = StrictPartialOrder(nodes=[order_process, order_execution])

# Defining execution order within the process
flush_process.order.add_edge(order_process, order_execution)
flush_process.order.add_edge(order_execution, place_order)

# This line of code makes sure the model is ready to be executed or analyzed with PM4Py
pm4py.visualization.powl.visualize(flush_process, filename="p2p.powl", debug=True)
```

This code configures a POWL model for a "Purchase-to-Pay" process. The model focuses on the core operations like recipient of the order confirmation, validating the order, placing the order, verifying the order, and a loop around the place and cancel order step. The flow uses an exclusive choice with 'OR' between the order confirmation, validate order steps, then uses a loop to handle either placing the order or cancel order, finally exclusive choice 'OR' with the choice of verifying the order or the place/order cycle. 

Important to note:

1. A simple visual representation of the process structure can be generated by this code. Users may need to adapt this to match the actual sequence of steps, in contrast to this represented example,

2. Function output such as the file name (`"p2p.powl"` in this case) is intended for illustrative purposes only. You can tailor this to your specific needs. 

3.