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  1. OMG Issue

DMN13 — No adjustment for last day in month if duration is added/subtracted to date and time value

  • Key: DMN13-24
  • Status: open  
  • Source: ACTICO ( Daniel Thanner)
  • Summary:

    The specification says that the addition/subtraction of a date and time and a years and months duration value is defined as:

    date and time (
       date(e1.year +/– e2.years + floor((e1.month+/– e2.months)/12),
       e1.month +/– e2.months – floor((e1.month +/– e2.months)/12) * 12,
       e1.day), 
       time(e1))
    

    If you apply this expression to the following two values:

    • date and time("2017-08-30T11:00:00Z")
    • duration("P18M")
      you would expect the following results:
    date and time("2017-08-30T11:00:00Z") + duration("P18M")  --> result should be date and time("2019-02-28T11:00:00Z")
    date and time("2017-08-30T11:00:00Z") - duration("P18M")  --> result should be date and time("2016-02-29T11:00:00Z")
    

    If you apply the values to the defined formula, you get:

    date and time (
       date(2017 +/– 1 + floor((8 +/– 6)/12),
       8 +/– 6 – floor((8 +/– 6)/12) * 12,
       30), 
       time("11:00:00Z"))
    

    Addition
    which results for addition into:

    date and time (
       date(2018 + floor(1,1667),
       14 – floor(1,1667) * 12,
       30), 
       time("11:00:00Z"))
    

    which is:

    date and time (date(2019, 2, 30), time("11:00:00Z"))
    

    The adjustment to the last valid day in a month is missing. 30th February is invalid, since February has only 28/29 days.

    Subtraction
    which results for subtraction into:

    date and time (
       date(2016 + floor(0,1667),
       2 – floor(0,1667) * 12,
       30), 
       time("11:00:00Z"))
    

    which is:

    date and time (date(2016, 2, 30), time("11:00:00Z"))
    

    The adjustment to the last valid day in a month is missing. 30th February is invalid, since February has only 28/29 days.

    Recommendation:
    Adjustment to last valid day in month must be added to spec.

  • Reported: DMN 1.1 — Mon, 2 Oct 2017 12:41 GMT
  • Updated: Mon, 8 Oct 2018 22:35 GMT