Most countries require that all bills passed by the house or houses of the legislature be signed into law by the head of state. In some states, such as the United Kingdom, Belgium and Ireland, the head of state is, in fact, formally considered a tier of the legislature. However, in most parliamentary systems, the head of state cannot refuse to sign a bill, and, in granting a bill their assent, indicate that it was passed in accordance with the correct procedures. The signing of a bill into law is formally known as "promulgation". Some monarchical states call this procedure "royal assent".