Validating XBRL instance documents in .NET

Question

Hi

I'm currently working with creation and validation of XBRL instance documents in C#, and I've run into some problems regarding the XBRL instance schema file:

http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd

According to the .NET schema validator, the schema is not valid. It throws the following exception:

System.Xml.Schema.XmlSchemaException: If ref is present, all of <complexType>, <simpleType>, <key>, <keyref>, <unique>, nillable, default, fixed, form, block, and type must be absent.

I get the same exception when I try to use the XML Schema Definition Tool (Xsd.exe) to generate a class representation of the schema.

This surprises me since XBRL is used in quite a lot of applications, and I can't find much information about this on the web. The an rather old discussion here which suggest that it depends on the tools used for the validation:

http://www.xml.com/cs/user/view/cs_msg/1849

This seems to be right since other schema validators do not complain. XMLSpy, XML Copy Editor and also w3's own validator

http://www.w3.org/2001/03/webdata/xsv#hlp-addr

validates the schema without any problems, where as XMLFox reports the same problem as .NET.

So my questions are:

• Is the XBRL instance schema valid? I suspect that the schema spec. might be unclear, so the authors of the different tool interpret it differently.
• What should I do if I want to work with the schema in .NET? Can you as a programmer, alter the validation engine rules in any way? Are there any other possibilities than the validation mechanisms in System.XML.Schema? Perhaps third party tool as Xerces in the Java world?

Thanks