diff --git a/man/htools.rst b/man/htools.rst
index 9f9a886bc8576553558e5172c9bf1e9fd3abf339..448afedc171814970c248cc2aca4837198d04047 100644
--- a/man/htools.rst
+++ b/man/htools.rst
@@ -154,7 +154,11 @@ support all options. Some common options are:
   page **htools**\(1).
 
   The file should contain text data, line-based, with single empty lines
-  separating sections. The lines themselves are column-based, with the
+  separating sections. In particular, an empty section is described by
+  the empty string followed by the separating empty line, thus yielding
+  two consecutive empty lines. So the number of empty lines does matter
+  and cannot be changed arbitrarily.
+  The lines themselves are column-based, with the
   pipe symbol (``|``) acting as separator.
 
   The first section contains group data, with the following columns: