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ORA-XQ-115-B: << and >> should be partial orders, only defined on trees, not between trees

From: Stephen Buxton <Stephen.Buxton@oracle.com>
Date: 16 Feb 04 13:06:08
Message-Id: <200402162106.i1GL68G06812@rgmgw5.us.oracle.com>
To: public-qt-comments@w3.org

SECTION 3.5.3: node comparisons

Regarding << and >>, I think that these should return true or 
false only when the comparands are nodes of some common supernode.
If x and y are in completely unrelated documents, how can you
decide whether x << y or x >> y?  I know that The Data Model
section 2.4 "Document order" says that there is an 
implementation-dependent total ordering of all documents which is
stable during the execution of an expression evaluation.  
An implementation-dependent order does not do the user any good,
and making it stable can not add value in the user's eyes 
to a feature with no value anyway.  This merely
burdens implementations with a useless requirement.
I think it would be preferable to say that << and >> are 
partial orders, returning an empty sequence if two nodes have no
common supernode.  

- Steve B.
Received on Monday, 16 February 2004 16:06:16 UTC

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