xsd extension sequence of extension-elements - xsd

Question

I would like to specify using xsd an xml-file of the form:
<root xsi:noNamespaceSchemaLocation="test2.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<mult>
<end />
<one>
<end />
</one>
<end />
<mult>
<end />
</mult>
<mult />
</mult>
</root>
That is, both, mult and end, instantiate a common abstract-type.
I am not clear how to define the type for mult without introducing further xml-elements as follows:
<root xsi:noNamespaceSchemaLocation="test2.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<mult>
<value>
<end />
</value>
<value>
<one>
<end />
</one>
</value>
<value>
<end />
</value>
<value>
<mult>
<value>
<end />
</value>
</mult>
</value>
<value>
<mult />
</value>
</mult>
</root>
for this latter file I can use:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:complexType name="TYPE_end" />
<xs:complexType name="TYPE_one">
<xs:complexContent>
<xs:extension base="TYPE_abstract" />
</xs:complexContent>
</xs:complexType>
<xs:complexType name="TYPE_mult">
<xs:sequence>
<xs:element name="value" type="TYPE_one" maxOccurs="unbounded" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="TYPE_abstract">
<xs:choice>
<xs:element name="end" type="TYPE_end" />
<xs:element name="one" type="TYPE_one" />
<xs:element name="mult" type="TYPE_mult" />
</xs:choice>
</xs:complexType>
<xs:element name="root" type="TYPE_abstract"/>
</xs:schema>
However, I do not know how to avoid the additional value-tag.
I could duplicate the list of elements as in the following example but this duplication is not nice as well...
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:complexType name="TYPE_end" />
<xs:complexType name="TYPE_one">
<xs:complexContent>
<xs:extension base="TYPE_abstract" />
</xs:complexContent>
</xs:complexType>
<xs:complexType name="TYPE_mult">
<xs:sequence>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="end" type="TYPE_end" />
<xs:element name="one" type="TYPE_one" />
<xs:element name="mult" type="TYPE_mult" />
</xs:choice>
</xs:sequence>
</xs:complexType>
<xs:complexType name="TYPE_abstract">
<xs:choice>
<xs:element name="end" type="TYPE_end" />
<xs:element name="one" type="TYPE_one" />
<xs:element name="mult" type="TYPE_mult" />
</xs:choice>
</xs:complexType>
<xs:element name="root" type="TYPE_abstract"/>
</xs:schema>
Any ideas how to provide a better solution?

Answer 1

Without more information about the rules for your XML, the following looks like it would work
<?xml version="1.0" encoding="utf-8" ?>
<!--Created with Liquid XML 2016 Developer Bundle Edition 14.1.4.6649 (https://www.liquid-technologies.com)-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:complexType name="TYPE_abstract">
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="end" />
<xs:element name="one" type="TYPE_abstract" />
<xs:element name="mult" type="TYPE_abstract" />
</xs:choice>
</xs:complexType>
<xs:element name="root" type="TYPE_abstract" />
</xs:schema>