SQL*Plus displays the version of Oracle to which you connected and the versions of available tools such as PL/SQL. The command prompt indicates that SQL*Plus is ready to accept your commands. If ...

NOLOG Establishes no initial connection to Oracle. Before issuing any SQL commands, you must issue a CONNECT command to establish a valid logon. Use /NOLOG when you want to have a SQL*Plus command ...

Running this SQL*Plus directive will execute ... execution plans for more information. This command will provide detailed statistics for the Oracle SQL. It will show the amount of time spent ...

and this configuration appears to be compatible both with Oracle's sqlplus command-line utility and with database links that are used for distributed transactions between multiple database instances.