diff --git a/mathml4-core.rnc b/mathml4-core.rnc
index d965c68..9adabe8 100644
--- a/mathml4-core.rnc
+++ b/mathml4-core.rnc
@@ -71,7 +71,6 @@ columnalignstyle = "left" | "center" | "right"
 notationstyle =
      "longdiv" |
      "actuarial" |
-     "radical" |
      "box" |
      "roundedbox" |
      "circle" |