XSD - Elements in any order and quantity (XML validated by XERCES using XSD)

Question

I have a problem with an XML schema. I need inside one element of an element of three types, but without any other restrictions, followed by exactly one occurrence of the element output:

<command path="app.exe" workingDir="/usr/local/bin">
    <param name="--name" assign="=">anyName</param>
    <switch name="--verbose"/>
    <param name="--config">/etc/app/conf.txt</param>
    <param name="--overriding">~/app/conf.txt</param>
    <switch name="-d"/>
    <param name="--report" assign="=">~/app/report.txt</param>
    <param name="--template">~/app/templates/default.tt</param>
    <string>../t/${testName}/log.txt</string>
    <output>
        <out path="stdout.txt"/>
        <err path="stderr.txt"/>
    </output>
</command>

I can use only sequence, allor choice, but none of them satisfies my requirement. Sequence - any number of times in the exact order. Everything is zero or once in any order. The choice is only one of them. I found one solution on this network , but it does not work with Xerces. I try this:

<xs:complexType name="commandType">
    <xs:sequence>
        <xs:group ref="gupa"/>
        <xs:element name="output" type="outputType" minOccurs="1" maxOccurs="1"/>
    </xs:sequence>
    <xs:attribute name="path" use="required" type="value"/>
    <xs:attribute name="workingDir" use="required" type="value"/>
</xs:complexType>

<xs:group name="gupa">
    <xs:choice>
        <xs:element name="env" type="pair" minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="param" type="paramType" minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="switch" type="switchType" minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="string" type="value" minOccurs="0" maxOccurs="unbounded"/>
    </xs:choice>
</xs:group>

But I get an error: Inappropriate content was found, starting with the 'switch' element. One of "{param, output}" is expected. There is a trick.

maxOccurs="unbounded" choice , .

, , : "maxOccurs" ""

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Answer 1

, .

  <xs:group name="mygr">
    <xs:choice>
      <xs:element name="string"></xs:element>
      <xs:element name="param"></xs:element>
      <xs:element name="switch"></xs:element>
      <xs:element name="env"></xs:element>
    </xs:choice>
  </xs:group>

  <xs:element name="root">
    <xs:complexType>
      <xs:sequence >
        <xs:sequence minOccurs="1" maxOccurs="unbounded">
          <xs:group ref="mygr"/>
        </xs:sequence>
        <xs:element name="output"></xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

, , .