Use the SHL (shift left) and SHR (shift right) commands to alter the
 left margin when in change mode.  The left margin is the position of the
 first character in each line on the screen.  Normally, the left margin
 is 0, which means all characters are displayed.  If you use a SHL
 command, the left margin can be changed by an integral number of tab
 stops (8 characters).  If SHL is used once, the first 8 columns will not
 be displayed on the screen.  This shifts the screen window horizontally.

 Format: countSHL  (Shift left by count tab stops)
         countSHR  (Shift right by count tab stops)