Data Description 
Loader provides you with functions for exporting, importing, transporting and formatting data between different data sources and data targets in different granularities.
Loader distinguishes between application data and metadata.
Application Data
Application data is the data that is stored in the database tables. Loader writes the application data to a data stream when exporting from the database system and to the database system when importing from a data stream.
Metadata
The database system manages its own metadata in the database catalog. For Loader, the metadata is the database system’s metadata plus the data that describes the application data, the database catalog information and the transformations according to the Loader’s requirements???.
Loader distinguishes between the metadata of the application data, database catalog, and transformation.
Metadata of the Application Data
The metadata of the application data (keyword DATA) is defined in the data streams using Loader commands and SQL statements. If the transformation spans multiple tables, Loader stores this information in the system tables. The corresponding data is stored in the database in the form of pages or rows, and in a data stream in the non-readable formats PAGES and RECORDS or in the readable formats CSV, FWV, FWV BINARY. If the data is transformed as rows, then columns of the external data type CHAR with the code attribute ASCII can be transformed into values of data fields with the code attribute ASCII, UCS-2, or UTF-8.
Metadata of the Database Catalog
Metadata of the database catalog (keyword CATALOG) describes the structure of the data in the database catalog. If the transformation spans multiple tables, Loader stores this information in its system tables. The corresponding data is stored in the database in the form of rows in the system tables and in a data stream in the form of SQL statements for data definition.
Metadata of the Transformation
The metadata of the transformations (keywords CONFIGURATION and PACKAGE) is declared in the form of Loader commands or in the form of Loader-specific system tables. This metadata describes the configuration and the runtime behavior of the transformations. The corresponding data, such as user names and table names, is stored, sorted by referential constraint conditions. In the database, the data is stored in the form of rows in the system tables in a data stream in the readable format CSV.