LITES2 accepts interactive input from a variety of devices. The devices available depend on the hardware that LITES2 is being run on and always include a terminal and possibly one or more of:

In addition facilities are available to accept LITES2 commands from additional serial devices. These could be additional terminals, mailboxes or even some other physical device attached by a serial line. At present there are 4 of these auxiliary input lines available, and they are accessed by the logical names:

If any of these logical names are set up when LITES2 is activated, then when interactive input is required, the program will accept LITES2 commands (as ASCII strings of up to 255 characters) from any of these devices.

Reading of interactive input is initiated by the triggering of an event flag, at which point all the interactive devices are checked to see if there has been any input. The auxiliary input devices are checked last, and they are all serviced before any more input is accepted. This means that no one input device can have exclusive control of LITES2; the input from the devices is generally interleaved.
There are obviously situations where it is necessary for a series of LITES2 commands to be executed sequentially, with no possibility of interruption from other devices. In this case the commands should be concatenated (with the concatenation character ) into one line. If a series of commands is required that when concatenated would make more than 255 characters, then a command file must be written, and then this can be read by using the file reading command @filename.