A more thorough explanation:

A sergeant-at-arms is an officer who has different roles depending on the context. Here are some of the most common definitions:

1. Historical: An armed officer who accompanies a sovereign.
2. Parliamentary: An officer assigned by the Crown to attend a session of Parliament.
3. Legislative: An officer responsible for maintaining order and serving notices and process on behalf of the legislative body and its committees.
4. Parliamentary law: An officer who helps keep order in a meeting under the chair's direction.

For example, in the United Kingdom, the Sergeant-at-Arms is responsible for security and ceremonial duties in the House of Commons and the House of Lords. In the United States, each chamber of Congress has its own Sergeant-at-Arms who is responsible for maintaining order and security during sessions and committee meetings.

Overall, a sergeant-at-arms is an important officer who helps ensure that proceedings are conducted in an orderly and efficient manner.