1 files changed, 4 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 3810d3db079..abebdf21135 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5501,6 +5501,8 @@ This is the same as (default-value 'left-margin).  */);
   DEFVAR_BUFFER_DEFAULTS ("default-tab-width",
                           tab_width,
                           doc: /* Default value of `tab-width' for buffers that do not override it.
+NOTE: This controls the display width of a TAB character, and not
+the size of an indentation step.
 This is the same as (default-value 'tab-width).  */);
 
   DEFVAR_BUFFER_DEFAULTS ("default-case-fold-search",
@@ -5692,6 +5694,8 @@ Linefeed indents to this column in Fundamental mode.  */);
   DEFVAR_PER_BUFFER ("tab-width", &BVAR (current_buffer, tab_width),
                      Qintegerp,
                      doc: /* Distance between tab stops (for display of tab characters), in columns.
+NOTE: This controls the display width of a TAB character, and not
+the size of an indentation step.
 This should be an integer greater than zero.  */);
 
   DEFVAR_PER_BUFFER ("ctl-arrow", &BVAR (current_buffer, ctl_arrow), Qnil,