diff --git a/share/mk/doc.docbook.mk b/share/mk/doc.docbook.mk
index bb90244dea..b75acc5388 100644
--- a/share/mk/doc.docbook.mk
+++ b/share/mk/doc.docbook.mk
@@ -338,7 +338,7 @@ NO_RTF=		yes
 schxslts+=	${sch}.xsl
 
 ${sch}.xsl: ${sch}
-	${XSLTPROC} ${XSLSCH} ${.ALLSRC} > ${.TARGET}
+	${XSLTPROC} --param allow-foreign "true" ${XSLSCH} ${.ALLSRC} > ${.TARGET}
 .endfor
 .endif
 
diff --git a/share/xml/freebsd.sch b/share/xml/freebsd.sch
index 96280fe675..4072cd66b8 100644
--- a/share/xml/freebsd.sch
+++ b/share/xml/freebsd.sch
@@ -2,11 +2,17 @@
 
 <!-- $FreeBSD$ -->
 
-<schema xmlns="http://purl.oclc.org/dsdl/schematron">
+<schema xmlns="http://purl.oclc.org/dsdl/schematron" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
   <pattern name="Check file reference validity">
     <rule context="//imagedata|//graphic">
-      <report test="contains(@fileref, '.')">Image references cannot have an extension; the proper format is inferred by the output type to generate.</report>
-      <report test="@format">Image format must not be specified; it is inferred by the output type to generate.</report>
+      <report test="contains(@fileref, '.')">Image reference (<xsl:value-of select="@fileref"/>) cannot have an extension; the proper format is inferred by the output type to generate.</report>
+      <report test="@format">Image reference (<xsl:value-of select="@fileref"/>) format must not be specified; it is inferred by the output type to generate.</report>
+    </rule>
+  </pattern>
+
+  <pattern name="Check cross-reference validity">
+    <rule context="//link">
+      <assert test="* or normalize-space()">Link (<xsl:value-of select="@linkend"/>) element must have a content; or use xref to auto-generate the linking text.</assert>
     </rule>
   </pattern>
 
@@ -20,10 +26,10 @@
 
   <pattern name="Check profiling attributes">
     <rule context="//*/@edition">
-      <assert test="(. = 'online') or (. = 'print')">The edition attribute can only be set to 'online' or "print".</assert>
+      <assert test="(. = 'online') or (. = 'print')">Invalid edition value (<xsl:value-of select="."/>); must be either 'online' or "print".</assert>
     </rule>
     <rule context="//*/@os">
-      <assert test="(. = 'freebsd8') or (. = 'freebsd9') or (. = 'freebsd10')">The os attribute can only be set to 'freebsd8', 'freebsd9' or 'freebsd10'.</assert>
+      <assert test="(. = 'freebsd8') or (. = 'freebsd9') or (. = 'freebsd10')">Invalid os value (<xsl:value-of select="."/>); must be either 'freebsd8', 'freebsd9' or 'freebsd10'.</assert>
     </rule>
   </pattern>
 </schema>