29310 2015-11-28 08:17:13 +0000 [FO31] Invalid and ambiguous XPath expression in normative part of section 5.4.3 fn:substring 2016-03-22 09:56:23 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Functions and Operators 3.1 Candidate Recommendation PC Windows NT CLOSED FIXED P2 normal --- 1 abel.braaksma mike public-qt-comments oldest_to_newest 124303 0 abel.braaksma 2015-11-28 08:17:13 +0000 Under 5.4.3 fn:substring we write: <quote> More specifically, the three argument version of the function returns the characters in $sourceString whose position $p satisfies: fn:round($start) <= $p < fn:round($start) + fn:round($length) </quote> But this is an illegal XPath expression. If it isn't meant to be an XPath expression, I thing the text should say so, but even then, the associativity is ambiguous. One might read this as: (fn:round($start) <= $p) < (fn:round($start) + fn:round($length)) or as: fn:round($start) <= ($p < fn:round($start)) + fn:round($length) But neither expressions make much sense in light of the text. Perhaps the following was meant (in which case parentheses are no longer necessary)? fn:round($start) <= $p and $p < fn:round($start) + fn:round($length) Alternatively, we might consider using the same approach as for fn:subsequence, which has a clearer way of defining in a proper XPath what the function is supposed to return. ------- Note that there are other places where ambiguous associativity is used, for instance '1<=N<=S" in fn:replace and "-π/2 <= θ <= +π/2" in math:asin, but in these case the textual context makes it clear that these are not meant to be read as XPath expressions, moreover, the mathematical meaning of "between" is easily deducted from the text. 124304 1 mike 2015-11-28 10:10:38 +0000 These expressions (A < B < C) were of course intended to be read as mathematical formulae rather than XPath expressions, but I take your point. 124391 2 mike 2015-12-08 16:17:21 +0000 Agreed that we will fix this by changing A < B <= C to (A lt B and B le C), i.e. to a valid XPath expression. Note that fn:subsequence is already written this way. 124440 3 mike 2015-12-16 12:26:08 +0000 The change has been applied.