olm -- Option Line Margin
default range syntax
1,$ olm[
]
Sets the left margin to which must be a positive integer.
This shifts the entire screen to the left; the characters that
were in columns 1 through - 1 will not be visible. You
may continue editing in the normal fashion. To reset your screen
to normal, enter the command "olm 1". If is omitted, the
current left margin column is displayed in the status line.
For general information about the options command, type "ho".