diff --git a/jsonschema-core.xml b/jsonschema-core.xml
index a8ca268f..006ea58a 100644
--- a/jsonschema-core.xml
+++ b/jsonschema-core.xml
@@ -516,13 +516,30 @@
                 locally named schemas.
             </t>
             <t>
-                Plain name fragments MUST start with a letter ([A-Za-z]) or underscore ("_"),
-                followed by any number of letters, digits ([0-9]), hyphens ("-"),
-                underscores ("_"), and periods (".").  This matches the US-ASCII part of XML's
+                Plain name fragments MUST follow XML's 
                 <xref target="xml-names">NCName production</xref>, which allows for compatibility
                 with the recommended plain name <xref target="W3C.REC-xptr-framework-20030325">syntax</xref> for
-                XML-based media types.
+                XML-based media types.  For convenience, the NCName syntax is reproduced here in ABNF form, using
+                a minimal set of rules:
+                <cref>
+                    Note that the previous syntax for plain name fragment is a subset of this syntax,
+                    which used only the first line of each of the NCNameStartChar and NCNameChar rules.
+                </cref>
             </t>
+            <sourcecode type="abnf"><![CDATA[
+NCName          = NCNameStartChar *NCNameChar
+
+NCNameStartChar = "_" / ALPHA
+                / %xC0-D6 / %xD8-F6 / %xF8-2FF
+                / %x370-37D / %x37F-1FFF
+                / %x200C-200D / %x2070-218F
+                / %x2C00-2FEF / %x3001-D7FF
+                / %xF900-FDCF / %xFDF0-FFFD
+                / %x10000-EFFFF
+
+NCNameChar      = NCNameStartChar / "-" / "." / DIGIT
+                / %xB7 / %x0300-036F / %x203F-2040
+]]></sourcecode>
             <t>
                 All fragment identifiers that do
                 not match the JSON Pointer syntax MUST be interpreted as