Final answer:
The 'initiate' property in the BPEL element can take the values 'yes' or 'no', determining whether a new process instance is created when a message is received.
Step-by-step explanation:
The initiate property in the BPEL <receive> element can take two values: yes or no. This property specifies whether a new process instance should be created when the message arrives. If yes is specified, the BPEL engine may create a new process instance upon the arrival of a message. If no is specified, the message is assumed to correlate to an existing process instance.