(Major Mode Conventions): A derived mode only needs to put the call to

[gnu-emacs] / lispref / positions.texi

diff --git a/lispref/positions.texi b/lispref/positions.texi
index 19a2675414080a8520c4a4af1437b091c721d09d..3c1e642e6b4c058c172bddae24b10c9be0cc41d0 100644 (file)
--- a/lispref/positions.texi
+++ b/lispref/positions.texi
@@ -15,14 +15,17 @@ speak of the character before or after a given position.  However, we
 often speak of the character ``at'' a position, meaning the character
 after that position.
 
-  Positions are usually represented as integers starting from 1, but can
-also be represented as @dfn{markers}---special objects that relocate
-automatically when text is inserted or deleted so they stay with the
-surrounding characters.  Functions that expect an argument to be a
-position (an integer), but accept a marker as a substitute, normally
-ignore the marker buffer.  Of course, markers used this way usually
-point to a position in the buffer that the function operates on, but
-that is entirely the programmer's responsibility.  @xref{Markers}.
+  Positions are usually represented as integers starting from 1, but
+can also be represented as @dfn{markers}---special objects that
+relocate automatically when text is inserted or deleted so they stay
+with the surrounding characters.  Functions that expect an argument to
+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, 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.
@@ -581,9 +584,9 @@ The coordinate arguments @var{frompos} and @var{topos} are cons cells of
 the form @code{(@var{hpos} . @var{vpos})}.
 
 The argument @var{width} is the number of columns available to display
-text; this affects handling of continuation lines.  Use the value
-returned by @code{window-width} for the window of your choice;
-normally, use @code{(window-width @var{window})}.
+text; this affects handling of continuation lines.  @code{nil} means
+the actual number of usable text columns in the window, which is
+equivalent to the value returned by @code{(window-width window)}.
 
 The argument @var{offsets} is either @code{nil} or a cons cell of the
 form @code{(@var{hscroll} . @var{tab-offset})}.  Here @var{hscroll} is