Re: [xml] Making sequence entries option in .xsd files.

[Steve Underwood <steveu coppice org>]

On 06/06/2016 07:52 PM, Steve Underwood wrote:
> Hi,
>
> In the .xsd file for the DLMS Smart Grid protocol I find the following 
> section:
>
> <xsd:complexTypename="InitiateRequest">
> <xsd:sequence>
> <xsd:elementname="dedicated-key"minOccurs="0"type="xsd:hexBinary"/>
> <xsd:elementname="response-allowed"default="true"type="xsd:boolean"/>
> <xsd:elementname="proposed-quality-of-service"minOccurs="0"type="Integer8"/> 
>
> <xsd:elementname="proposed-dlms-version-number"type="Unsigned8"/>
> <xsd:elementname="proposed-conformance"type="Conformance"/>
> <xsd:elementname="client-max-receive-pdu-size"type="Unsigned16"/>
> </xsd:sequence>
> </xsd:complexType>
>
> By the protocol definition, the first 3 items in that sequence should 
> be optional. The minOccurs="0" elements cause items 1 and 3 to be 
> correctly treated as optional. However, the parser in libxml2 2.9.3 
> treats the second item as a required element. Shouldn't the default 
> setting act in a similar way to a minOccurs="0" element, in making the 
> item optional? Is it always necessary to have minOccurs="0" present 
> when default="something" is present, in order to actually implement 
> the default?
>
> Regards,
> Steve 
I have been reading the XSD spec again, and it seems to me the line
<xsd:elementname="response-allowed"default="true"type="xsd:boolean"/>
in the above XSD definition needs minOccurs="0" adding to it to make the 
element optional. I can't find anything in the spec that says 
default="xx" has any effect other than to set a default value.

Can anyone confirm or refute this?

Regards,
Steve