Title is required on preface

diff --git a/docbook/relaxng/src/hier.rnc b/docbook/relaxng/src/hier.rnc
index 7c23f2a97f893818310e27a1dded4f97f8343fea..94a8ed97733535f7a0711a7a7c626589984d78a2 100644 (file)
--- a/docbook/relaxng/src/hier.rnc
+++ b/docbook/relaxng/src/hier.rnc
@@ -328,7 +328,7 @@ div {
     & db.label.attribute?
     & db.preface.status.attribute?
 
-   db.preface.info = db._info
+   db.preface.info = db._info.title.req
 
    db.preface =
       element preface {