Version: SMASH-2.2
ListBox

The ListBox modus provides an option to initialize a box with a given set of particles. This modus uses all functionality from the List modus itself. The only difference is that one has to specify the length of the box.

Modi:
    ListBox:
        File_Directory: "particle_lists_in"
        File_Prefix: "event"
        Shift_Id: 0
        Length: 10.0

Apart from that the usage should be equivalent to the List modus. So for more details please check the List userpage.