Note that upon deleting some persons, the PID no longer matches with the index, With John Doe at index 4 having a PID of 6, John Doe at index 5 having a PID of 7, Roy Balakrishnan at index 6 having a PID of 5

Edit: Upon further reading, understand that this is intended, but may be good to add a clarification that PID should not be used to refer to persons in the Address Book, and instead used for internal/other purposes.
Note that upon deleting some persons, the PID no longer matches with the index, With John Doe at index 4 having a PID of 6, John Doe at index 5 having a PID of 7, Roy Balakrishnan at index 6 having a PID of 5

Edit: Upon further reading, understand that this is intended, but may be good to add a clarification that PID should not be used to refer to persons in the Address Book, and instead used for internal/other purposes.