need help with meaning of this schema

[cat5ive]

Hi,

I'm trying to learn xml schema. Is the code below mean element billOfLading can contain either element masterBill or houseBill but not both? How can I modify it so that it can contain either masterBill or houseBill or both.
And at lease one of them (masterBill or houseBill) must be present in billOfLading.
Thank in advance

<xs:complexType name="data">
<xs:sequence>
<xs:element name="actionCode" type="xs:string">
<xs:element name="billOfLading" type="bl" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>

<xs:complexType name="bl">
<xs:sequence>
<xs:choice>
<xs:element name="masterBill" type="mbl"/>
<xs:element name="houseBill" type="hbl"/>
</xs:choice>
</xs:sequence>
</xs:complexType>

 

[tsuji]

[1] Q: >Is the code below mean element billOfLading can contain either element masterBill or houseBill but not both?
A: It means that.

[2] Q: >How can I modify it so that it can contain either masterBill or houseBill or both.
[2.1] A1: No specific ordering imposed, plus condition "or none".
[tt]
<xs:complexType name="bl">
<xs:all>
<xs:element name="masterBill" type="mbl" minOccurs="0" />
<xs:element name="houseBill" type="hbl" minOccurs="0" />
</xs:all>
</xs:complexType>
[/tt]
[2.2] A2: With specific ordering that masterBill if exists appears before houseBill, plus condition "or none".
[tt]
<xs:complexType name="bl">
<xs:sequence>
<xs:element name="masterBill" type="mbl" minOccurs="0" />
<xs:element name="houseBill" type="hbl" minOccurs="0" />
</xs:sequence>
</xs:complexType>
[/tt]
[2.3] Q: >And at lease one of them (masterBill or houseBill) must be present in billOfLading.
A: W3C schema language, as expressive as it be, cannot express this condition. One needs alternative to impose that constraint.

 

[cat5ive]

Thank you,tsuji.

 

[cat5ive]

One more question.
Is it illegal to defind 'type' both in element declaration and inside simpleType, see below.

      <xs:element name="itemDescription" [COLOR=red]type="xs:string" [/color]minOccurs="0">
		<xs:simpleType>
 		     <xs:restriction [COLOR=red]base="xs:string">[/color]
			<xs:maxLength value="50"/>	
		     </xs:restriction>
	       </xs:simpleType>
	    </xs:element>

When I tried to open the file with software Altova XMLSpy, I got the error message below and the word element is highlighted.
The 'type' attribute and an anonymous type definition are mutually exclusive for element declaration 'itemDescription'.

 

[tsuji]

[3] Q: >Is it illegal to defind 'type' both in element declaration and inside simpleType.
A: It is. The point is that with the simpleType contained inside the xs:element tag, you are on the way to define a simple type, anonymous and local to the element. Hence, it is contradictory to the parser being told it is of type xs:string.

[3.1] If you want to define a custom simpleType to be declared in the xs:element tag as an attribute, you can make it named with global in scope. It would be available by then to be referred to in other places in the schema. Like this.
[tt]
<xs:simpleType name="x">
<xs:restriction base="xs:string">
<xs:maxLength value="50"/>
</xs:restriction>
</xs:simpleType>
<xs:element name="itemDescription" type="[red]x[/red]" minOccurs="0" />
[/tt]