System Tables is the powerful feature which is uses to track the database objects and it should not be altered directly by any user, Do not attempt to modify System Tables with DELETE, UPDATE, or INSERT statements, or user-defined triggers. System Tables are much like the tables you create in a database with a few exceptions. These tables are identified internally as system objects so that you can differentiate your regular tables from System Tables and some system tables are inherently read only. System Tables are documented for a better understanding of how Teradata RDBMS works internally.