default:
>       1       2       3       4       5       6       7       8       9      0

clear non-existant:    x                    x
>       1       2       3       4       5       6       7       8       9      0

clear 2 and 4:  x               x
>       1               3               5       6       7       8       9      0

clear 0:                                                                       x
>       1               3               5       6       7       8       9      0

clear after 0:                                                                 .
x
>       1               3               5       6       7       8       9      0

clear all:
>                                                                              0
done

TBC at end with clipping:             ABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890abcd!