Waaw — unrestricted conjunction: “دخل زيد وعمرو” says that both entered without necessarily fixing an order.
Faa — close succession: “دخل زيد فعمرو” presents the second entry as following the first in connected sequence.
Thumma — delayed succession: “دخل زيد ثم عمرو” presents a meaningful interval before the second entry.
In legal application, establish the particle's function first, then determine whether the complete expression is a report, condition, permission, or legal disposition. The particle is one foundation of the ruling; the full sentence and its requirements must also be examined.