points into, at the marker position. The marker position advances as
characters are inserted. The value of point in the buffer has no effect
on printing when the stream is a marker, and this kind of printing
-does not move point.
+does not move point (except that if the marker points at or before the
+position of point, point advances with the surrounding text, as
+usual).
@item @var{function}
@cindex function output stream