indicate what it is. @xref{Minor Modes}, for more information about
minor modes and about how to use this command.
+@cindex narrowing, and line number display
+ If you have narrowed the buffer (@pxref{Narrowing}), the displayed
+line number is relative to the accessible portion of the buffer.
+
@vindex line-number-display-limit
If the buffer is very large (larger than the value of
@code{line-number-display-limit}), then the line number doesn't appear.
Emacs doesn't compute the line number when the buffer is large, because
-that would be too slow. Set it to @code{nil} to remove the limit. If
-you have narrowed the buffer (@pxref{Narrowing}), the displayed line
-number is relative to the accessible portion of the buffer.
+that would be too slow. Set it to @code{nil} to remove the limit.
+
+@vindex line-number-display-limit-width
+ Line-number computation can also be slow if the lines in the buffer
+are too long. For this reason, Emacs normally doesn't display line
+numbers if the average width, in characters, of lines near point is
+larger than the value of the variable
+@code{line-number-display-limit-width}. The default value is 200
+characters.
@cindex Column Number mode
@cindex mode, Column Number