be a position (an integer), but accept a marker as a substitute,
normally ignore which buffer the marker points into; they convert the
marker to an integer, and use that integer, exactly as if you had
-passed the integer as the argument. Markers used this way usually
-point to a position in the buffer that the function will operate on,
-but if not, they are converted to integers anyway. @xref{Markers}.
+passed the integer as the argument, even if the marker points to the
+``wrong'' buffer. A marker that points nowhere cannot convert to an
+integer; using it instead of an integer causes an error.
+@xref{Markers}.
See also the ``field'' feature (@pxref{Fields}), which provides
functions that are used by many cursor-motion commands.