Just an addition to the "isValidDchar" function :

--- utf.d.orig  Wed Sep 29 04:25:49 2004
+++ utf.d       Thu Oct 28 00:01:50 2004
@@ -40,6 +40,15 @@
     }
 }

+bit isAscii(char c)
+{
+    return c <= 0x7F;
+}
+
+bit isSurrogate(wchar c)
+{
+    return (c >= 0xD800 && c <= 0xDFFF);
+}

 bit isValidDchar(dchar c)
 {

Perhaps obvious to all Unicode experts, but anyway...

--anders