current buffer.
The arguments @var{front-advance} and @var{rear-advance} specify the
-insertion type for the start of the overlay and for the end of the
-overlay, respectively. @xref{Marker Insertion Types}. If
-@var{front-advance} is non-@code{nil}, text inserted at the beginning
-of the overlay is excluded from the overlay. If @var{read-advance} is
-non-@code{nil}, text inserted at the beginning of the overlay is
-included in the overlay.
+marker insertion type for the start of the overlay and for the end of
+the overlay, respectively. @xref{Marker Insertion Types}. If they
+are both @code{nil}, the default, then the overlay extends to include
+any text inserted at the beginning, but not text inserted at the end.
+If @var{front-advance} is non-@code{nil}, text inserted at the
+beginning of the overlay is excluded from the overlay. If
+@var{rear-advance} is non-@code{nil}, text inserted at the end of the
+overlay is included in the overlay.
@end defun
@defun overlay-start overlay