The term "system" is most frequently used by the people of the United Empire of Earth (UEE) as shorthand for planetary system, or the grouping of all planetary bodies and other satellites that orbit a given star. The planets of a particular planetary system are by default given the name of the star they circle followed by a Roman numeral, ordered beginning with I as the innermost planet. Satellites of those planets are designated with an Arabic numeral matching the planet they orbit followed by a lowercase letter starting with a for the innermost moon. Less frequently, system may refer to a star system, or a group of multiple stars which are impacted by one another's gravity and proximity.