diff --git a/README.pod b/README.pod
index d3b8261..ce3ea97 100644
--- a/README.pod
+++ b/README.pod
@@ -586,7 +586,8 @@ C<--xticlabels>
 If given, the x-axis tic labels are not numerical, but are read from the data.
 This changes the interpretation of the input data: with C<--domain>, each line
 begins with C<x label ....>. Without C<--domain>, each line begins with C<label
-...>. This makes sense only without C<--3d>. Please see the guide
+...>. This does I<not> affect the tuple size. This makes sense only without
+C<--3d>. Please see the guide
 (L<https://github.com/dkogan/feedgnuplot/blob/master/guide/guide.org>) for usage
 examples.
 
diff --git a/bin/feedgnuplot b/bin/feedgnuplot
index a18a852..1442b02 100755
--- a/bin/feedgnuplot
+++ b/bin/feedgnuplot
@@ -1995,7 +1995,8 @@ C<--xticlabels>
 If given, the x-axis tic labels are not numerical, but are read from the data.
 This changes the interpretation of the input data: with C<--domain>, each line
 begins with C<x label ....>. Without C<--domain>, each line begins with C<label
-...>. This makes sense only without C<--3d>. Please see the guide
+...>. This does I<not> affect the tuple size. This makes sense only without
+C<--3d>. Please see the guide
 (L<https://github.com/dkogan/feedgnuplot/blob/master/guide/guide.org>) for usage
 examples.
 
diff --git a/guide/guide.org b/guide/guide.org
index f0ebcf3..0d6b2e8 100644
--- a/guide/guide.org
+++ b/guide/guide.org
@@ -538,7 +538,8 @@ These aren't "histograms", where gnuplot bins the data for us, but rather the
 data is given to us, ready to plot. We pass =--xticlabels= to indicate that the
 x-axis tic labels come from the data. This changes the interpretation of the
 input: with =--domain=, each line begins with =x label ....=. Without
-=--domain=, each line begins with =label ...=.
+=--domain=, each line begins with =label ...=. This does /not/ affect the
+tuple size.
 
 Basic example without =--domain=: