> I use XML Spy, which does not seem to support the following
> to format a date as Hijri:
>
> <xsl:value-of
> select="format-date(pp:DateOfBirthHijri,'[D&#x0661;] [Mn]
> [Y&#x0661;]', 'ar', 'AH')"/>

The format-date() function must have either 2 or 5 arguments. You seem to
have 4. You've left out the last one, which is country (it can be set to
"()").
>
> Has anyone else tried this? Does Saxon or any other processor
> support this?

Saxon has no support for non-Gregorian calendars. You can write a
localization module for the "ar" language, but not for the "AH" calendar.
>
> Incidentally, in the XSLT 2.0 specification, the format for
> this is shown as
>
> format-date( $value  as xs:date?, $picture  as xs:string, $language
>  as xs:string?, $calendar  as xs:string?, $country
>  as xs:string?) as xs:string?
>
> But one of the examples is
>
> format-date($d, "[D&#x0661;] [Mn] [Y&#x0661;]", "Islamic",
> "ar", "AH", ())

This is fixed in erratum XT.E23:

http://www.w3.org/XML/2007/qt-errata/xslt-errata.html#E23

Regards,

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