Make targetdoc optional on olink

diff --git a/docbook/relaxng/docbook/src/pool.rnc b/docbook/relaxng/docbook/src/pool.rnc
index 047d3abf6c97350dad122b2d581f09055530d7ba..43953d28616429c8199edfbc52e6a3fe542c1bad 100644 (file)
--- a/docbook/relaxng/docbook/src/pool.rnc
+++ b/docbook/relaxng/docbook/src/pool.rnc
@@ -7414,7 +7414,7 @@ div {
 
    db.olink.attlist =
       db.common.attributes
-    & db.olink.targetdoc.attribute
+    & db.olink.targetdoc.attribute?
     & db.olink.role.attribute?
     & db.olink.xrefstyle.attribute?
     & db.olink.localinfo.attribute?