NM-F&O-8: fn:sum, fn:min, fn:max

I think it's editorial error:

If input sequence is not empty, doesn't contains NaN's and error is not raised,
the result of the function is defined as result of the expression:

$c[1] + fn:sum(subsequence($c, 2))

So in last recursion, when count($c)=1, fn:sum is called again with empty sequence as parameter
and returns 0.0e0 of type double. When sequence contains values of types other than numeric (dayTimeDuration etc),
addition will raise type error. According to this fn:sum will not work for sequence of any types other than numeric...

Also this expression should be defined for two-argument version of fn:sum and say that second argument is assumend 0.0e0
if not specified. It should be:

if (count($c)=1)
    $c[1]
else
    $c[1] + fn:sum(subsequence($c, 2),$zero)




Similar definitions in fn:min and fn:max are not clear:
"If the items in the value of $arg are of type xs:string or types derived by restriction from xs:string, then the determination of the greatest item is made according to the collation that is used."

"according to the collation" is not precise, expression with fn:compare should be used.
Plus there are two typos in expressions used for general case: ')' on end of first line and ']' on end of third
and variable $collation mentioned below expression is not used.

Best Regards,
Noe Michejda
7th Portal S.C.