Three completely new protected directories were introduced because of platform security:
\sys
All executable native code resides in \sys\bin.
A flat directory — all EXE files, DLLs, etc. must have a different name.
TCB capability is required to modify the \sys contents.
AllFiles capability is enough to read \sys (file
browser, diagnostics tools).
\resource
Read-only resource files are shared by (potentially) all applications.
Applications without any capabilities can read these files.
TCB capability is required to modify the \resource contents.
The software installer adds and updates these files, but nothing else.
Subdirectories can be utilized to ensure file-name uniqueness.
\private
\private\<process SID> is the private
directory of the process specified with the SID.
Processes have full access only to their own directory.
Other processes need the AllFiles capability to be able to access (read and write) the other private directories.
These protected directories are located on either fixed or removable drives. All the other (previously used) directories are unprotected, so all applications in a device can access them.
For more detailed information, see File Locations in the Symbian OS Library.