2 files changed, 8 insertions, 5 deletions

diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
index c8987c279c5..01f899f1c09 100644
--- a/doc/emacs/display.texi
+++ b/doc/emacs/display.texi
@@ -1601,7 +1601,6 @@ screen lines.  Setting the variable @code{truncate-lines} in any way
 makes it local to the current buffer; until that time, the default
 value, which is normally @code{nil}, is in effect.
 
-@vindex truncate-partial-width-windows
   If a split window becomes too narrow, Emacs may automatically enable
 line truncation.  @xref{Split Window}, for the variable
 @code{truncate-partial-width-windows} which controls this.
diff --git a/doc/emacs/windows.texi b/doc/emacs/windows.texi
index 7587f885a23..702963f75c5 100644
--- a/doc/emacs/windows.texi
+++ b/doc/emacs/windows.texi
@@ -117,10 +117,14 @@ variable @code{truncate-lines} (@pxref{Line Truncation}); it is
 instead controlled by the variable
 @code{truncate-partial-width-windows}.  If the value of this variable
 is a positive integer (the default is 50), that specifies the minimum
-width for a partial-width window before automatic line truncation
-occurs; if the value is @code{nil}, automatic line truncation is
-disabled; and for any other non-@code{nil} value, Emacs truncates
-lines in every partial-width window regardless of its width.
+total width for a partial-width window before automatic line
+truncation occurs; if the value is @code{nil}, automatic line
+truncation is disabled; and for any other non-@code{nil} value, Emacs
+truncates lines in every partial-width window regardless of its width.
+The total width of a window is in column units as reported by
+@code{window-total-width} (@pxref{Window Sizes,,, elisp, The Emacs
+Lisp Reference Manual}), it includes the fringes, the continuation and
+truncation glyphs, the margins, and the scroll bar.
 
   On text terminals, side-by-side windows are separated by a vertical
 divider which is drawn using the @code{vertical-border} face.