The Clave Unica de Registro de Poblacion (also known as the Personal ID Code Number) is a unique identifying code for both Mexican citizens and residents. It is used by government agencies to identify individuals for various purposes including but not limited to: health care, social security, taxation, etc. The CURP is printed on most official documents including birth certificates, death certificates, marriage licenses, and divorce decrees. It can also be found in the data file of the Sistema de Administración Tributaria (Tax Administration System). The CURP consists of numbers and letters that are combined together to create a unique identification number. The combination of numbers and letters must adhere to certain rules when created. There are two methods used to create the CURP: manually and automatically. For manual processing, each person assigned a CURP should do so in person at a local registry office. Agencies that conduct automated processes should do so using validated electronic files containing information about existing citizens. These files are called datos autonómicos en síntesis (DAS). Birth certificates issued after January 1, 2004, contain an additional field called RUT. This is an abbreviation for "ruta legal tuya" or "legal route to your address".