shifts the text on lines between the mark and the cursor either right (‘>’, the default) or left (‘<’) by adding or removing white space on each line. The adjustment size, specified as an unsigned integer ‘n’, is in units of the current tab size (‘t’) or spaces (‘s’). The default is 1. Adjustments start at the left edge of a vertical mark, or column 1 otherwise. If the mark is not currently set, only the current line is affected.
Shift will insert tab characters only if the document’s
flag and the
ShiftTabs flag are both set—in which case an upper case
‘T’ will appear in the status bar. If either of the
ShiftTabs flags is unset (i.e there is no upper case ‘T’ in the
Shift will only insert spaces.
In the case of left shifts, if any indicated line has insufficient leading
white space for the requested adjustment to be made, then
reports an error and makes no changes.