Application file system.

The DATA or DATA_TOP directory is located on the database server machine, and contains the system tablespaces, redo log files, data tablespaces, index tablespaces, and database files.

The DB directory is located on the database server machine, and contains the ORACLE_HOME for the Oracle9i database.

The APPL or APPL_TOP directory contains the product directories and files for Oracle Applications.

The ORA directory contains the ORACLE_HOMEs for the Applications technology stack components.

The COMN or COMN_TOP (or COMMON_TOP) directory contains directories and files used across products.