AT&T 6300 Programmer's Manual page 502

WIDTH
Statement
7-346
WIDTH LPRINT size
Sets the line width at the line printer.
WIDTH size or WIDTH "SCRN:",size
Sets the screen width (in Text mode), selects a
text window or changes mode (in Graphics
mode). Changing the screen or text window
width, or the mode, causes the screen to be
cleared.
In Text Mode (mode 0) "size" may only have
the values 40 or 80, selecting either a 40-
column or an 80-column screen.
In Graphics Mode (mode 1, 2, or 100) you can
either change mode or select a text window of
width 40 or 80. The width of the function key
display will correspond to the selected width. If
the number of columns displayed is 40 you may
enter CTRL-T to scroll the function key display
horizontally.