I thought I'd let you know about an interesting processing error that occurred today when testing IBM DFDL. An expression of the form: {if (fn:exists(x) and fn:contains('abc', x/y)) then 1 else 0} gave a parser error saying that x/y didn't exist, when x was not in the message. This surprised me, as I was assuming that the IBM DFDL parser would lazily evaluate the operands of the logical expression. I was going to raise a bug, but thought I had best read the XPath 2.0 spec first. The relevant section is here: http://www.w3.org/TR/xpath20/#id-logical-expressions The section says that unless you are in XPath 1.0 compatibility mode (which a DFDL processor would not be), the order of evaluation of operands of a logical expression is actually implementation dependent. So it is therefore unsafe to rely on lazy evaluation to implement a guard in the manner that I had. I have rewritten the expression as: {if (fn:exists(x)) then if (fn:contains('abc', x/y)) then 1 else 0 else 0} I think this might catch people out and is certainly worthy of mention in (at least) a tutorial on DFDL expressions. Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 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