The /opt directory
The /opt directory contains the actual system software in
a series of subdirectories known as ``software storage objects''
or SSOs. All system utilities in the root filesystem
(such as /usr, /bin, and so on) are actually
links to an SSO. /opt contains the shared
files of SSOs that can be used by clients of
a server system, while /var contains the non-shared
``Software storage objects'' in the Networking Guide
manual page for more information.