ISO/IEC 9075 defines the SQL language. The scope of the SQL language is the definition of data structure and the operations on data stored in that structure. Parts 1, 2 and 11 encompass the minimum requirements of the language. Others parts define extensions.
ISO/IEC 9075-9:2003 defines extensions to SQL to support management of external data through the use of foreign-data wrappers and datalink types.