Joe Correct that circular references are a schema definition error but the specification doesn't say that explicitly. I will add it to the (newly created) list of errata Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell@uk.ibm.com From: Joe Futrelle <futrelle@ncsa.uiuc.edu> To: Alan Powell/UK/IBM@IBMGB Cc: "Robert E. McGrath" <remcgrat@illinois.edu> Date: 11/02/2011 17:42 Subject: question for the working group Section 7.2.1 describes how a dfdl:defineFormat can include a ref on its enclosed dfdl:format, to establish inheritance among defined formats. It is therefore possible to express circular inheritance patterns: <dfdl:defineFormat name="deadly"> <dfdl:format ref="embrace" ... /> </dfdl:defineFormat> <dfdl:defineFormat name="embrace"> <dfdl:format ref="deadly" .../> </dfdl:defineFormat> I assume circular inheritance ought to be schema definition error; does the spec say that, anywhere? -- Joe Futrelle Cyberenvironments and Technologies National Center for Supercomputing Applications http://www.ncsa.uiuc.edu/People/futrelle Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU