XML Schema: Unsequenced After Sequenced

I want a preamble, followed by unordered data

[cmarshall]

I'll be investigating how to do this myself, but it would be timesaving if someone already has the answer.

Basically, what I want is the ability to specify a schema for this type of XML:

<container> 
 <preamble></preamble> 
 <someDataType1></someDataType1> 
 <someDataType2></someDataType2> 
 <someDataType1></someDataType1> 
 <someDataType3></someDataType3> 
</container> 

The idea is that the header will always be the first item, followed by an unordered list of subsequent items.

The problem comes when I try to specify that the preamble comes first, but anything goes after that.

<xs:all> [w3schools.com] allows arbitrary order. The problem is that I want to insist that the

<preamble>

element must always be first.

I can do it by enclosing the subsequent data in another container, but I'd like to try to avoid that if I can.

It does not look like you can have both an <xs:all> [w3schools.com] and an <xs:sequence> [w3schools.com] in the same <xs:complexType> [w3schools.com] element.

This is what I'd like to see:

<xs:element name="container"> 
 <xs:complexType> 
  <xs:sequence> 
   <xs:element name="preamble"></xs:element> 
   <xs:all> 
    <xs:element name="someDataType1"></xs:element> 
    <xs:element name="someDataType2"></xs:element> 
    <xs:element name="someDataType3"></xs:element> 
   </xs:all> 
  </xs:sequence> 
 </xs:complexType> 
</xs:element> 

I hope that makes it clear. For the record, the schema above does not work. It is merely a way of specifying a concept.

[cmarshall]

Okay, further investigating...

This will work:

<?xml version="1.0" encoding="UTF-8"?> 
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
  <xs:complexType name="header"> 
    <xs:sequence> 
      <xs:element name="preamble"> </xs:element> 
    </xs:sequence> 
  </xs:complexType> 
  <xs:complexType name="data"> 
    <xs:all> 
      <xs:element name="data_item1"> </xs:element> 
      <xs:element name="data_item2"> </xs:element> 
      <xs:element name="data_item3"> </xs:element> 
    </xs:all> 
  </xs:complexType> 
  <xs:element name="AutoBuildReadMe"> 
    <xs:complexType> 
      <xs:sequence> 
        <xs:element name="head" type="header"/> 
        <xs:element name="body" type="data"/> 
      </xs:sequence> 
    </xs:complexType> 
  </xs:element> 
</xs:schema> 

However, this is NOT what I want. I don't want a "head" and a "body" section. I want to have their contents without the envelopes.

[cmarshall]

This won't work:

<?xml version="1.0" encoding="UTF-8"?> 
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
 <xs:group name="datagroup"> 
  <xs:all> 
   <xs:element name="data_item1"/> 
   <xs:element name="data_item2"/> 
   <xs:element name="data_item3"/> 
  </xs:all> 
 </xs:group> 
  
 <xs:element name="AutoBuildReadMe"> 
  <xs:complexType> 
   <xs:sequence> 
    <xs:element name="preamble"/> 
    <xs:group ref="datagroup"/> 
   </xs:sequence> 
  </xs:complexType> 
 </xs:element> 
</xs:schema>

However, THIS will:

<?xml version="1.0" encoding="UTF-8"?> 
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
 <xs:group name="datagroup"> 
  <xs:sequence> <!-- We use xs:sequence here, instead of xs:all --> 
   <xs:element name="data_item1"/> 
   <xs:element name="data_item2"/> 
   <xs:element name="data_item3"/> 
  </xs:sequence> 
 </xs:group> 
  
 <xs:element name="AutoBuildReadMe"> 
  <xs:complexType> 
   <xs:sequence> 
    <xs:element name="preamble"/> 
    <xs:group ref="datagroup"/> 
   </xs:sequence> 
  </xs:complexType> 
 </xs:element> 
</xs:schema>

I need to be able to allow the following fields to be randomly-ordered.

[cmarshall]

One of my employees applied some non-linear thinking, and came up with the solution:

<?xml version="1.0" encoding="UTF-8"?> 
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
  <xs:element name="root"> 
    <xs:complexType> 
      <xs:sequence> 
        <xs:element name="preamble"/> 
        <xs:sequence> 
          <xs:choice maxOccurs="unbounded"> 
            <xs:element name="data1"/> 
            <xs:element name="data2"/> 
            <xs:element name="data3"/> 
          </xs:choice> 
        </xs:sequence> 
      </xs:sequence> 
    </xs:complexType> 
  </xs:element> 
</xs:schema>

The way this works is that the

<xs:choice/>

element turns the

<xs:sequence/>

element into a de facto

<xs:all/>

element.