[F&O] 15.1.14 fn:unordered

There are two issues with this function:

 1. The description is confusing: 
    “This function takes a sequence, or more typically, an expression, 
     that evaluates to a sequence, as input .”
    
Is “an expression, that evaluates to a sequence” a separate datatype in
Xpath/Xquery 2.0? This phrase is not necessary, confusing and has to be
removed. All other functions "take an expression" that evaluates to the
necessary argument types -- we know this and don't need to be told this
just for one specific function.


 2. There isn't a meningful example to demonstrates the usefulness of this
function. The explanation given does not tell the reader when and why to
use the function:

"Query optimizers may be able to do a better job if the order of the
output sequence is not specified. For example, if you want to retrieve all
the prices from a purchase order, and if there is an index on prices, it
may be possible to compute an unordered result more efficiently."

This tells the reader why he/she may receive unordered sequence as result,
not why and when he/she should use fn:unordered() to provide an unordered
sequence to other functions.


Dimitre Novatchev.



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