Sets the left margin for the current buffer to the column number you
  specify.

  By default, LSE sets the indicated buffer's left margin at column 1.
  The column number you specify must be an integer less than the value
  set for the right margin.

  If you specify column number 0, LSE uses the indentation of the
  current line to determine the left margin when you use the SET
  LANGUAGE WRAP command.  Having set the left margin to 0, when you
  enter the FILL command LSE uses the indentation of the first line of
  each selected paragraph to determine the left margin.