The difference between two dates is a dayTimeDuration (if they're in the
same timezone - the usual case - then it will be an integer number of days).

Subtraction of dates to give a yearMonthDuration - the old
subtractDateTimesYieldingYearMonthDuration - has been removed (as befits any
function with such a ridiculous name) because it proved too difficult to
specify it. For example, would you expect 2005-02-28 minus 2005-01-31 to be
one month, on the basis that 2005-01-31 plus one month is 2005-02-28? But
surely the difference between these two dates is the same as 2004-02-28
minus 2004-01-31?

Depending what you actually want to achieve, the best approach is probably
to extract the year/month components (year-from-date(), month-from-date())
and manipulate the values yourself.

Michael Kay
http://www.saxonica.com/  

> -----Original Message-----
> From: Pawson, David [mailto:David.Pawson@xxxxxxxxxxx] 
> Sent: 01 March 2005 15:51
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  xslt 2. Date arithmetic.
> 
> 
> <xsl:variable name="t1" 
>    select="xs:date('2002-09-01')"/>
>  <xsl:variable name="t2" select="current-date()" />
> 
>  <xsl:variable name="dur" 
>    select="xdt:yearMonthDuration($t2 - $t1)"  
> as="xdt:yearMonthDuration"
>    />
> 
>  <xsl:sequence
>  select="$dur" /> 
> 
> 
> I'm getting casting errors, and I can't see a way of resolving it.
> Error on line xx:
>   FORG0001: Cannot convert to yearMonthDuration because some 
> components are non-
> zero
> Transformation failed: Run-time errors were reported
> 
> yes.... agree they are non-zero. 
> 
> 
> 
> Any help appreciated.
> 
> 
> Regards DaveP.
> 
> **** snip here *****
> 
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