<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:simpleType name="S1">
        <xsd:restriction base="xsd:string">
            <xsd:minLength value="10"/>
        </xsd:restriction>
    </xsd:simpleType>
    <xsd:simpleType name="S2">
        <xsd:restriction base="S1">
            <xsd:maxLength value="20"/>
        </xsd:restriction>
    </xsd:simpleType>
</xsd:schema>