29749 2016-07-21 19:23:08 +0000 [fo31] Rounding of fractional seconds in format-time() 2016-12-16 19:55:15 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Functions and Operators 3.1 Candidate Recommendation PC All CLOSED FIXED P2 normal --- 1 mike mike andrew_coleman christian.gruen tim public-qt-comments oldest_to_newest 127029 0 mike 2016-07-21 19:23:08 +0000 Over ten years ago, as a result of bug #3018, the following sentence was added to the spec: In the case of the fractional seconds component, the value is rounded to the specified size as if by applying the function round-half-to-even(fractional-seconds, max-width). and it seems this has gone unchallenged since. So what exactly is the output of format-time(xs:time("12:01:01.9999", "[s99].[f99]")) In particular, how does one round a fractional seconds value such as .9999 to a maximum width of two digits by following the round-half-to-even rule? 127041 1 mike 2016-07-22 15:29:09 +0000 It's hard to come up with a fully satisfactory solution to this. I think we should rule out all solutions that attempt to round 01.9999 "properly" to 02.0000, changing the seconds value, because it would be very disruptive for the formatting of one component to affect the output of another. I think there are two possible choices: (A) Abandon rounding and switch to truncation. Truncation always works and is consistent with the general approach of the function: if the value is 12:59:59 and you choose not to output the seconds, the output is 12:59, not 13:00. It's an incompatible change, but it's a change to something that can never have worked properly. (B) Specify that if rounding the fractional seconds would cause the seconds value to change, we truncate instead. So 1.9999 "rounds" to 1.99. I think my preference is to take the compatibility hit and go for (A). 127042 2 mike 2016-07-22 16:54:40 +0000 >So what exactly is the output of >format-time(xs:time("12:01:01.9999", "[s99].[f99]")) For Saxon, in recent releases at any rate, the output has been "01.00". Not nice. 127054 3 mike 2016-07-26 19:22:33 +0000 The WG decided on option (A) in comment (1): switch to truncating rather than rounding. 127056 4 mike 2016-07-26 19:55:22 +0000 The spec and test cases have been updated. 127096 5 christian.gruen 2016-08-01 08:34:50 +0000 Wouldn’t it make sense to also apply the rule to fn:dateTime? If yes, I guess that the following testcases should be revised: * format-dateTime-002g * format-dateTime-002h * format-dateTime-002i * format-dateTime-003m * format-dateTime-003n * format-dateTime-003p * format-dateTime-013s * format-dateTime-013u 127098 6 mike 2016-08-01 10:08:18 +0000 Yes the new rule obviously applies to fn:format-dateTime() as well, and there may well be other test cases that need updating. 127104 7 tim 2016-08-05 15:37:12 +0000 I have taken the liberty of correcting the expected results for these tests. 127269 8 andrew_coleman 2016-09-02 10:47:10 +0000 Based on Tim's comment #7, I have marked this bug as resolved/fixed. Please reopen if you believe any more work needs to be done. Thanks.