Recursive allow hack for RELAX NG

any_content.rng

<?xml version="1.0" encoding="UTF-8"?>
<grammar 
    xmlns="http://relaxng.org/ns/structure/1.0"
    xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
    datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
    <start>
        <choice>
            <ref name="any_content"/>            
        </choice>
    </start>
    
    <!-- This is a strange little group of definitions that allow for anything recusively downsteam -->
    <define name="any_content">
        <interleave>
            <zeroOrMore>
                <ref name="any_element"/>
            </zeroOrMore>
            <text/>
        </interleave>
    </define>
    
    <define name="any_element">
        <element>
            <anyName/>
            <zeroOrMore>
                <ref name="any_attribute"/>
            </zeroOrMore>
            <zeroOrMore>
                <ref name="any_content"/>
            </zeroOrMore>
        </element>
    </define>
    
    <define name="any_attribute">
        <attribute>
            <anyName/>
        </attribute>
    </define>    
    
</grammar>