The English description for the validation rule ird-10 seems to be missing a key piece of information: “The first day is the day of the month from firstRegularPeriodStartDate if it exists, otherwise from effectiveDate/unadjustedDate. The second day is the lesser of the rollConvention, and the firstRegularPeriodStartDate if it exist or the effectiveDate/unadjustedDate if it doesn’t. The first day must equal the second day.” The XPath description makes it clear that the second day is the lesser of the rollConvention and the *last day of the month of* the firstRegularPeriodStartDate etc., but there is no mention of the “last day of the month” in the English description.
