--- a/RelaxNG/publidoc.rnc	jeu. déc. 19 18:48:33 2013 +0100
+++ b/RelaxNG/publidoc.rnc	jeu. déc. 19 22:46:32 2013 +0100
@@ -741,7 +741,8 @@
 math = element math { math.attributes, math.content }
 
 math.attributes =
-   math.display.attribute?
+   xmlid.attribute?
+ & math.display.attribute?
 math.display.attribute = attribute display {
    "wide" | "numbered" | "box"  | "numbered-box" }