In the 2070's identification plays a substantial part of your life. You are frequently scanned for your SIN even as you do something simple like walking down the street or entering a building.
Since ID plays such an important role in society, there are many different types you can have. Below are some of the more common types in Boston.
Legal SIN: This is how the UCAS government tracks you. It is easily accessible and tracable by anyone.
Fake SIN: This is a generic fake ID. It lets you act more or less anoymously for daily tasks.
Green SIN: This is not an officially recognized SIN designation. It is used to indicate it is a SIN tracked by the Irish Mafia. In effect it can be considered a legal SIN when the mafia is concerned and may open (or shut) doors as appropriate.
Shadow SIN: This is not an officially recognized SIN designation. It is used to indicate it is a SIN tracked by the Syndicate. The true effects of this are unknown.
Errant SIN: This is an officially recognized SIN designation. This IS is in the Knight Errant computers and as such is available to all law enforcement, UCAS government, and Ares megacorp. SINs of this type will open many doors. This is the complete opposite of a Criminal SIN.
Criminal SIN: This is an officially recognized SIN designation. This SIN has a criminal record tracked by both the UCAS government and all law enforcement. This SIN will shut many doors.
Corporate SIN: This is a generic designation for a SIN granted by a corporation. Each SIN is tied to a particular corp and will grant appropriate access within it. There are various degrees of this type of SIN, for instance you can have a security clearance or a normal worker clearance.
Runners and those will extremely low lifestyles tend to find themselves among the SINless. This may be a deliberate act, or it may be a side effect of living on the streets. The SINless are non-entities as far as the government and law are concerned and as such have no rights. Even those who deliberate erased their history recognize the need of having an ID to fall back on for day to day activities.