# op:subtract-yearMonthDuration-from-dateTime - XPath XQuery Reference

Returns the xs:dateTime that is a given duration before a specified
               xs:dateTime (or after, if the duration is negative).Defines the
         semantics of the "-" operator when applied to an xs:dateTime and an
            xs:yearMonthDuration value. deterministiccontext-independentfocus-independentThe function returns the xs:dateTime computed by negating
               $arg2 and adding the result to the value of $arg1 using the
            function op:add-yearMonthDuration-to-dateTime.op:subtract-yearMonthDuration-from-dateTime(xs:dateTime("2000-10-30T11:12:00"),
                  xs:yearMonthDuration("P1Y2M"))xs:dateTime("1999-08-30T11:12:00")