<\body> A session can be started from the menu. Since is based on the language, it is always possible to start a session using . On systems, it is usually also possible to start shell sessions using . The remainder of the items in the menu depend on the plug-ins which are installed on your system. A session consists of a sequence of input and output fields and possible text between them. When pressing inside an input field of a session, the text inside the environment is evaluated and the result is displayed in an output field. When entering a command in a session, the application attempts to execute it. Several commands may be launched concurrently in the same document, but the output will only be active in the session where the cursor is and at the place of the cursor. Therefore, we recommend to use different buffers for parallel executions. For each type of extern application, one may choose between sharing a single process by different sessions, or launching a separate process for each different session. More precisely, when inserting a session using , you may specify both a ``session type'' (Shell, Pari, Maxima, ) and a ``session name'' (the default name is ``default''). Sessions with different names correspond to different processes and sessions with the same name share a common process. In order to finish the process which underlies a given session, you may use . When pressing in the input of a non-connected system, the system will be restarted automatically. You may also use in order to interrupt the execution of a command. However, several applications do not support this feature. In order to evaluate all fields of a previously created session, you may use . Similarly, and allow you to evaluate all field above or below the current field. <\initial> <\collection>