SID

A Standard Identifier, also known as a SID, is a unique sequence of alpha-numeric characters that can directly represent a person, vehicle, location, or object. While initially enforced in the Pact Worlds as a way of identifying citizens and their vessels, the use of SIDs has expanded across the civilized members of the galaxy, and is a common first step in vetting new arrivals to a planet's galactic border. In the modern era SIDs are also used by cellular and email providers, and are therefore commonly traded among acquaintances as a convenient means of contact.