In fact Saxon doesn't accept any kind of constructor (direct or computed) after a leading "/", and it doesn't accept an ordered{} or unordered{} expression either, all of which are legal according to the BNF. 
I think there is room for debate on what is legal here, and I have therefore raised a bug against the spec: see
I won't change the Saxon parser until the WG rules on this bug.
Michael Kay

From: [] On Behalf Of Rademacher, Gunther
Sent: 01 June 2008 21:24
To: Mailing list for the SAXON XSLT and XQuery processor
Subject: [saxon] XQuery syntax error

Saxon's XQuery parser apparently does not accept a direct constructor
following a leading slash in a path expression, as in


The resulting expression may not be particularly useful, but isn't it
valid per the grammar in the XQuery recommendation?

Best regards,

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