--- a/RelaxNG/publiquiz.rnc	mer. août 14 20:01:39 2019 +0200
+++ b/RelaxNG/publiquiz.rnc	jeu. août 15 10:55:28 2019 +0200
@@ -170,7 +170,7 @@
 
 blanks-fill.content =
     (blanks.block+ | blanks.section+),
-    keyboard
+    keyboard?
 blanks-select.content =
     blanks.intruders?,
     (blanks.block+ | blanks.section+)