Governors-general are frequently accorded the status and privileges of a head of state at diplomatic events when considered as representing their absentee monarch, but not as themselves heads of state.
Hereditary Prince Alois is permanent representative for exercising the sovereign powers due to Liechtenstein Prince Hans-Adam II.
However, in many cases it is not this neutral principle but national rules of protocol that are acted upon, usually by an international event's host nation, as in many bilateral and even certain multilateral occasions.
Even in the presence of one or more Heads of State, certain occasions are governed by specific protocol, e.g. military.
Thus in many cases precedence is given to monarchs over republican heads of state, mostly in monarchies; in some nations, the Pope (himself a monarchical head of state) ranks above secular heads of state, especially in Roman Catholic countries.