Add RELAX NG schema for XRC files.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74927 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/doxygen/overviews/xrc_format.h

@@ -22,6 +22,9 @@
 This document describes the format of XRC resource files, as used by
 wxXmlResource.
 
+Formal description in the form of a RELAX NG schema is located in the
+@c misc/schema subdirectory of the wxWidgets sources.
+
 XRC file is a XML file with all of its elements in the
 @c http://www.wxwidgets.org/wxxrc namespace. For backward compatibility,
 @c http://www.wxwindows.org/wxxrc namespace is accepted as well (and treated

misc/schema/xrc_schema_builtin_only.rnc

@@ -0,0 +1,12 @@
+#
+# RELAX NG schema for XRC files.
+#
+# Super-strict variant that only accepts wx's builtin classes.
+#
+# See http://docs.wxwidgets.org/trunk/overview_xrcformat.html for freeform
+# description of the format.
+#
+
+include "xrc_schema.rnc" {
+  customClasses = notAllowed
+}