Tis Veugen wrote:


>>><xsd:complexType name="ct1">
>>>  <xsd:choice>
>>>    <xsd:sequence>
>>>      <xsd:attribute name="type" type="st1" fixed="v1"/>
>>>      <xsd:element name="str" type="string"/>
>>
>>Have you actually tried to use that schema with a validating XML parser or 
>>a schema parser? It would tell you that the xsd:attribute is not allowed 
>>inside of the xsd:sequence.
> 
> 
> The XRay XML Editor does not complain about it.
> According to my book , XML Developer's Guide, it's allowed.

That is odd, here is the official documentation of the sequence element:
   <http://www.w3.org/TR/xmlschema-1/#element-sequence>
it says the allowed content of sequence is:
   Content: (annotation?, (element | group | choice | sequence | any)*)
so an attribute declaration does not belong there, you can start with an 
optional annotation and then element or group or choice or nested 
sequence or any (element).

> Otherwise, how could such a choice of 3 possibilities regarding attributes 
> be modelled?

The choice element is not for attributes but for a choice model for 
complex element content.
As for attributes you can declare an attribute to be optional, you can 
declare a default value or even a fixed value but you cannot model 
constraints between a possible attribute value and the element content 
model as you seem to try to do. Not with the W3C schema language in its 
current version at least.



-- 

	Martin Honnen --- MVP XML
	http://JavaScript.FAQTs.com/