The state is a basic international legal entity and as such carries a broad set of rights and obligations. It is understandable that all the changes that affect its constitutive elements are dragging behind them a number of tasks necessary to solve outstanding issues.
The widest status changes cause t. i. the succession of states, which both the Vienna Convention on Succession (international treaties and state property, debts and archives) define as "the replacement of one State with another in respect of responsibility for the international relations of an individual territory"