This parameter specifies the name of the file from which the APL session (⎕SE ) is to be loaded when APL starts. If not specified, a .dse extension is assumed. This session file contains the ⎕SE object that was last saved in it. This object defines the appearance and behaviour of the Session menu bar, tool bar(s) and status bar, together with any functions and variables stored in the ⎕SE namespace.

See also Session file.