Custom Handlers for Listers: Trapped Functions

Messages for  trapped commands  are sent to the lister much like the other
messages.

The message arguments are:-

        Arg0 - <command>           (name of the command, or 'abort')
        Arg1 - <handle>            (source lister handle, if any)
        Arg2 - <files>             (selected files, if any)
        Arg3 - <handle>            (destination lister handle, if any)
        Arg4 - <path>              (source path; useful if there's no lister
                                   associated with it)
        Arg5 - <args>              (user-supplied arguments to the function)
        Arg7 - <path>              (destination path; allows you to support
                                   the Select Destination requester)
        Arg8 - <functionhandle>    (If  synctraps  flag is set, contains
                                   address in decimal of structure for this
                                   function)

The filenames are separated by spaces (if there is more than one), and will
be within quotes if the quotes keyword was specified for the
 lister set handler  command.

You should not rely on the ARexx Word() function to traverse the list
of filenames because it does not support quotes and any name with a space
in it will cause your script to malfunction.