<Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2012) (Learn how and when to remove this template message) </Td> </Tr> <P> Some academic writers discuss states and governments in terms of "models". </P> <P> An independent nation state normally has a head of state, and determines the extent of its head's executive powers of government or formal representational functions . In protocolary terms, the head of a sovereign, independent state is usually identified as the person who, according to that state's constitution, is the reigning monarch, in the case of a monarchy, or the president, in the case of a republic . </P> <P> Among the different state constitutions (fundamental laws) that establish different political systems, four major types of heads of state can be distinguished: </P>

In a republican state the head of the state is