SET(LEFT_MARGIN)
     Allows you to set the left margin without setting the right margin.
  Syntax
     SET (LEFT_MARGIN, buffer, integer)
  Parameters
     buffer               The buffer in which the margin is to be set.
     integer              The column at which the margin is to be set.  The
                          value must be greater than 0 and less than the
                          value of the right margin.
  Example
     The following statement causes the left margin of the buffer contained
     in the variable 'my_buffer' to be set to 5.  The right margin is left
     unchanged.
     SET (LEFT_MARGIN, my_buffer, 5);
  Related Topics
     SET(RIGHT_MARGIN)