<P> In parliamentary systems, approval is normally a formality, since the head of state is directed by an executive controlled by the legislature . In constitutional monarchies, this approval is called royal assent . In rare cases approval may be refused or "reserved" by the head of state's use of a reserve power . The legislature may have significantly less power to introduce bills on such issues and may require the approval beforehand . In Commonwealth realms the royal prerogative informs this . In the United Kingdom, for example, cases include payments to the royal family, succession to the throne, and the monarch's exercise of prerogative powers . </P> <P> In presidential systems, the need to receive approval can be used as a political tool by the executive, and its refusal is known as a veto . The legislature may be able to override the veto by means of a supermajority vote . </P> <P> A bill may come into force as soon as it becomes law, or it may specify a later date to come into force, or it may specify by whom and how it may be brought into force; for example, by ministerial order . Different parts of an act may come into force at different times . </P> <P> An act is typically promulgated by being published in an official gazette . This may be required on enactment, coming into force, or both . </P>

When is a bill given a name and number